目前更新到70题！
目前WA：飞机起飞速度；字符串替换；GPS通信协议。
前言
代码均可AC，解析参见我的博客 NOJ(C)易错总结 (annesede.github.io)。（已更新到70题！）
部分题目由于过于简单一次性AC，未能考虑可读性（其实是懒得改）。
题目分类如下，请按题目名称查找：
- 入门题：只涉及基本的输入输出
- 简单题：不涉及算法但有较多易错点
- 中等题：涉及简单的算法或数学知识
- 难题：涉及复杂的算法或数学知识
入门题
Hello World
#include<stdio.h>
int main(){
printf("Hello World");
return 0;
}A+B
#include<stdio.h>
int main(){
int a = 0, b = 0;
scanf("%d %d",&a,&b);
printf("%d",a+b);
return 0;
}数据类型大小及范围
#include <stdio.h>
#include <limits.h>
int main(){
int id = 0;
scanf("%d",&id);
switch (id) {
case 1: // char
printf("%llu,%d,%d\n",sizeof(char),CHAR_MIN,CHAR_MAX);
break;
case 2: // unsigned char
printf("%llu,%u,%u\n",sizeof(unsigned char),0,UCHAR_MAX);
break;
case 3: // short
printf("%llu,%hd,%hd\n",sizeof(short),SHRT_MIN,SHRT_MAX);
break;
case 4: // unsigned short
printf("%llu,%hu,%hu\n",sizeof(unsigned short),0,USHRT_MAX);
break;
case 5: // int
printf("%llu,%d,%d\n",sizeof(int),INT_MIN,INT_MAX);
break;
case 6: // unsigned int
printf("%llu,%u,%u\n",sizeof(unsigned int),0,UINT_MAX);
break;
case 7: //long
printf("%llu,%ld,%ld\n",sizeof(long),LONG_MIN,LONG_MAX);
break;
case 8: // unsigned long
printf("%llu,%u,%lu\n",sizeof(unsigned long),0,ULONG_MAX);
break;
case 9: // long long
printf("%llu,%lld,%lld\n",sizeof(long long),LLONG_MIN,LLONG_MAX);
break;
case 10: // unsigned long long
printf("%llu,%u,%llu\n",sizeof(unsigned long long),0,ULLONG_MAX);
break;
}
return 0;
}平均值
#include <stdio.h>
int main(){
int a = 0, b = 0;
scanf("%d %d",&a,&b);
int c = ((b-a)>>1)+a;
printf("%d",c);
return 0;
}进制转换
#include <stdio.h>
int main(){
unsigned int a = 0;
scanf("%d",&a);
printf("%X,%o",a,a);
return 0;
}浮点数输出
#include <stdio.h>
int main(){
double a = 0.0f;
scanf("%lf",&a);
printf("%.6lf,%.2lf,%.8lf",a,a,a);
return 0;
}动态宽度输出
#include <stdio.h>
int main(){
int n = 0, m = 0, k = 0;
scanf("%d %d",&n,&m);
int tmp = n;
while (tmp) {
tmp /= 10;
++k;
}
for (int i = 0; i < m-k; ++i) {
printf("%d",0);
}
printf("%d",n);
return 0;
}计算地球上两点之间的距离
#include <stdio.h>
#include <math.h>
#define RADIUS 6371.000000
#define PI 3.1415926
int main(){
double phi1, phi2, lambda1, lambda2, distance;
scanf("%lf %lf",&phi1,&lambda1);
scanf("%lf %lf",&phi2,&lambda2);
phi1 = phi1*PI/180;
phi2 = phi2*PI/180;
lambda1 = lambda1*PI/180;
lambda2 = lambda2*PI/180;
double havRatio = (1-cos(phi2-phi1))/2+cos(phi1)*cos(phi2)*(1-cos(lambda2-lambda1))/2;
distance = asin(sqrt(havRatio))*2*RADIUS;
printf("%.4lfkm",distance);
return 0;
}风寒指数
#include <stdio.h>
#include <math.h>
int main(){
double v,T;
scanf("%lf %lf",&v,&T);
int chill = 13.12f+0.6215f*T-11.37f*pow(v,0.16f)+0.3965f*T*pow(v,0.16f)+0.5f;
printf("%d",chill);
return 0;
}乘数模
#include <stdio.h>
int main(){
long long a,b,m,r;
scanf("%lld %lld %lld",&a,&b,&m);
r = ((a%m)*(b%m))%m;
printf("%lld",r);
return 0;
}组合数
#include<stdio.h>
int main(){
int cnt = 0, n, m;
scanf("%d",&n);
for(int a = 0; a <= 9; ++a){
for(int b = 0; b <= 9; ++b){
for(int c = 0; c <= 9; ++c){
for(int d = 0; d <= 9; ++d){
m = a+b+c+d;
if (m == n){
++cnt;
}
}
}
}
}
printf("%d",cnt);
return 0;
}余数和
#include <stdio.h>
int main() {
unsigned int sum = 0, n, k;
scanf("%u %u",&n,&k);
for (unsigned int i = 1; i <= n; ++i) {
sum += k%i;
}
printf("%u",sum);
return 0;
}佩尔数
#include <stdio.h>
int PA(int n){
if (n == 0) return 0;
else if (n == 1) return 1;
return 2*PA(n-1)+PA(n-2);
}
int PB(int n){
int p0 = 0, p1 = 1, pn;
for (int i = 0; i <= n; ++i) {
if (i == 0) pn = p0;
else if (i == 1) pn = p1;
else {
pn = 2 * p1 + p0;
p0 = p1;
p1 = pn;
}
}
return pn;
}
int main() {
int n, p;
scanf("%d",&n);
if (n&1) p = PA(n);
else p = PB(n);
printf("%d",p);
return 0;
}可变参数累加
#include <stdio.h>
#include <stdarg.h>
int sum(int start,...){
va_list vaList;
int sum = 0;
va_start(vaList,start);
while (start){
sum += start;
start = va_arg(vaList,int);
}
va_end(vaList);
return sum;
}
int main() {
int a,b,c,d,e,f;
scanf("%d %d %d %d %d %d",&a,&b,&c,&d,&e,&f);
int sumMinus = sum(a,b,0) - sum(c,d,e,f,0);
printf("%d",sumMinus);
return 0;
}可变参数平均
#include <stdio.h>
#include <stdarg.h>
double avg(int num,...){
va_list vaList;
double sum = 0.0f;
va_start(vaList,num);
for (int i = 0; i < num; ++i) {
sum += va_arg(vaList,int);
}
va_end(vaList);
return sum/num;
}
int main() {
int a,b,c,d,e;
scanf("%d %d %d %d %d",&a,&b,&c,&d,&e);
double avgMinus = avg(2,a,b) - avg(3,c,d,e);
printf("%.4f",avgMinus);
return 0;
}航空旅行
#include <stdio.h>
#include <stdbool.h>
void pass(int a, int b, int c, int d, int e) {
bool flag = false;
if (a <= e && (b + c) <= d) flag = true;
if (b <= e && (a + c) <= d) flag = true;
if (c <= e && (a + b) <= d) flag = true;
if (flag) printf("YES\n");
else printf("NO\n");
}
int main() {
int n, a, b, c, d, e;
scanf("%d",&n);
while (n--){
scanf("%d %d %d %d %d", &a, &b, &c, &d, &e);
pass(a, b, c, d, e);
}
return 0;
}波士顿房价预测
#include <stdio.h>
double nAvg(double arr[], int n) {
double sum = 0;
for (int i = 0; i < n; ++i) {
sum += arr[i];
}
return sum / n;
}
int main() {
int n;
scanf("%d", &n);
double x[n], y[n];
for (int i = 0; i < n; ++i) {
scanf("%lf %lf", &x[i], &y[i]);
}
double xBar = nAvg(x, n), yBar = nAvg(y, n);
double sumUp = 0, sumDown = 0;
for (int i = 0; i < n; ++i) {
sumUp += (x[i] - xBar) * (y[i] - yBar);
}
for (int i = 0; i < n; ++i) {
sumDown += (x[i] - xBar) * (x[i] - xBar);
}
double b = sumUp / sumDown;
double a = yBar - b * xBar;
printf("Y=%.4lf+%.4lf*X",a,b);
return 0;
}蒙特卡罗方法求积分
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
double func1(double x) {
return pow(x, 4) * exp(-x);
}
double func2(double x) {
return x * x + 1;
}
double func3(double x) {
return cos(x);
}
double func4(double x) {
return sqrt(x) * (x - 2);
}
double func5(double x) {
return 2 * sin(x) - 5 * cos(x);
}
double func(int m, double x) {
switch (m) {
case 1: return func1(x);
case 2: return func2(x);
case 3: return func3(x);
case 4: return func4(x);
case 5: return func5(x);
default: return 0;
}
}
double mtk(int m, double a, double b, int n) {
srand(RAND_MAX);
double w = b - a, sum = 0;
for (int i = 1; i < n; ++i) {
double x = ((double)rand() / RAND_MAX) * w + a;
sum += func(m, x);
}
sum *= w / n;
return sum;
}
int main() {
int m, n;
double a, b;
scanf("%d %lf %lf %d", &m, &a, &b, &n);
printf("%.6lf", mtk(m, a, b, n));
return 0;
}大小写交换
#include <stdio.h>
void strSwapCase(char str[]) {
for (int i = 0; str[i] != '\0'; ++i) {
if ('a' <= str[i] && str[i] <= 'z')
str[i] = (char) str[i] - 'a' + 'A';
else if ('A' <= str[i] && str[i] <= 'Z')
str[i] = (char) str[i] - 'A' + 'a';
}
}
int main() {
char str[1000] = "";
scanf("%[^\n]", str);
strSwapCase(str);
puts(str);
return 0;
}DNS双螺旋结构
#include <stdio.h>
void putsDna1(){
printf(" AT \n");
printf(" T--A \n");
printf(" A----T \n");
printf("T------A\n");
printf("T------A\n");
printf(" G----C \n");
printf(" T--A \n");
printf(" GC \n");
}
void putsDna2(){
printf(" CG \n");
printf(" C--G \n");
printf(" A----T \n");
printf("A------T\n");
printf("T------A\n");
printf(" A----T \n");
printf(" A--T \n");
printf(" GC \n");
}
void putsDna3(){
printf(" AT \n");
printf(" C--G \n");
printf(" T----A \n");
printf("C------G\n");
printf("C------G\n");
printf(" T----A \n");
printf(" G--C \n");
printf(" AT \n");
}
int main() {
int n;
scanf("%d", &n);
for (int i = 1; i <= n/2; ++i) {
if (i % 3 == 1) putsDna1();
else if (i % 3 == 2) putsDna2();
else putsDna3();
}
return 0;
}PID控制
#include <stdio.h>
typedef struct PIDController {
double Kp, Ki, Kd;
double preError, integral;
} PIDData;
double PIDCalculate(PIDData *pid, double setPoint, double measuredValue) {
double error = setPoint - measuredValue;
pid->integral += error;
double differential = error - pid->preError;
double output = pid->Kp * error + pid->Ki * pid->integral + pid->Kd * differential;
pid->preError = error;
return output;
}
int main() {
double setPoint, measuredValue;
int time;
PIDData pid = {0};
scanf("%lf %lf %lf", &pid.Kp, &pid.Ki, &pid.Kd);
scanf("%lf %lf %d", &setPoint, &measuredValue, &time);
for (int i = 1; i <= time; ++i) {
double output = PIDCalculate(&pid, setPoint, measuredValue);
measuredValue += output;
printf("%d %.6lf\n", i, measuredValue);
}
return 0;
}简单题
颜色模型转换
#include <stdio.h>
#include <stdio.h>
#include <math.h>
double findmax(double a, double b, double c) {
return a >= b ? (a >= c ? a : c) : (b >= c ? b : c);
}
double findmin(double a, double b, double c) {
return a <= b ? (a <= c ? a : c) : (b <= c ? b : c);
}
int main()
{
int R, G, B;
double r, g, b;
double max, min;
double H, S, V;
scanf("%d %d %d",&R,&G,&B);
r = (double)((R > 0 ? R : 0) / 255.0f);
g = (double)((G > 0 ? G : 0) / 255.0f);
b = (double)((B > 0 ? B : 0) / 255.0f);
max = findmax(r, g, b);
min = findmin(r, g, b);
V = max;
if (max < 1e-9) {
S = 0.0f;
}
else {
S = (max - min) / max;
}
if (max - min < 1e-9) {
H = 0.0f;
}
else {
if (max == r) {
H = 60.0f * (g - b) / (max - min);
}
else if (max == g) {
H = 60.0f * (2.0f + (b - r) / (max - min));
}
else if (max == b) {
H = 60.0f * (4.0f + (r - g) / (max - min));
}
else {
return -1;
}
if (H < 1e-9) {
H = H + 360.0f;
}
}
printf("%.4lf,%.4lf%%,%.4lf%%", H, S * 100, V * 100);
return 0;
}方阵
#include <stdio.h>
int main(){
int n,m;
scanf("%d",&n);
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
m = (i-j) > 0 ? (i-j) : (j-i);
printf("%d ",m);
}
printf("\n");
}
return 0;
}分数的加、减、乘、除
#include <stdio.h>
int gcd(int a,int b) {
if (b == 0) return a;
else return gcd(b,a%b);
}
int main() {
int a,b,c,d;
scanf("%d",&a);
getchar();
scanf("%d",&b);
getchar();
scanf("%d",&c);
getchar();
scanf("%d",&d);
printf("(%d/%d)+(%d/%d)=%d/%d\n",a,b,c,d,(a*d+b*c)/gcd(a*d+b*c,b*d),b*d/gcd(a*d+b*c,b*d));
printf("(%d/%d)-(%d/%d)=%d/%d\n",a,b,c,d,(a*d-b*c)/gcd(a*d-b*c,b*d),b*d/gcd(a*d-b*c,b*d));
printf("(%d/%d)*(%d/%d)=%d/%d\n",a,b,c,d,(a*c)/gcd(a*c,b*d),b*d/gcd(a*c,b*d));
printf("(%d/%d)/(%d/%d)=%d/%d\n",a,b,c,d,(a*d)/gcd(a*d,b*c),b*c/gcd(a*d,b*c));
return 0;
}
操作数
#include <stdio.h>
int sumDig(int n){
int sum = 0;
while(n){
sum += n%10;
n /= 10;
}
return sum;
}
int main(){
int n,cnt=0;
scanf("%d",&n);
while(n){
n -= sumDig(n);
++cnt;
}
printf("%d",cnt);
return 0;
}比率
#include <stdio.h>
#include <math.h>
int gcd(int a,int b){
if (b == 0) return a;
else return gcd(b,a%b);
}
int cntDig(double x){
int cnt = 0;
while(x != floor(x)){
++cnt;
x *= 10;
}
return cnt;
}
int main(){
double x;
scanf("%lf",&x);
int cnt = cntDig(x), n, m, g;
m = pow(10,cnt);
n = (int)(x*m);
g = gcd(m,n);
m /= g;
n /= g;
printf("%d/%d",n,m);
return 0;
}级数和
#include <stdio.h>
#include <math.h>
double decimal (int n){
double m = (double)n+1;
while(floor(m)){
m /= 10;
}
return m+n;
}
int main(){
int n;
scanf("%d",&n);
double sum = 0.0f, term;
for (int i = 1; i < n; ++i) {
term = decimal(i);
sum += term;
printf("%g+",term);
}
term = decimal(n);
sum += term;
printf("%g=%g",term,sum);
return 0;
}对称数
#include <stdio.h>
int main(){
int n;
scanf("%d",&n);
int a = (n/100)%10;
int b = (n/10)%10;
int c = n%10;
if ((b == 0 || b == 1 || b == 8) && ((a == 6 && c == 9) || (a == 9 && c == 6)
|| ((a == 0 || a == 1 || a == 8) && (c == 0 || c == 1 || c == 8)))){
printf("Yes\n");
} else {
printf("No\n");
}
return 0;
}
倍数和
#include <stdio.h>
int main(){
unsigned int t = 0;
scanf("%u", &t);
unsigned int arrn[t];
for(unsigned int i = 0; i < t; i++){
scanf("%u", &arrn[i]);
}
for(unsigned int j = 0; j < t; j++){
unsigned int res = 0;
for(unsigned int x = 1; x < arrn[j]; x++){
if(x % 3 == 0 || x % 5 == 0){
res += x;
}
}
printf("%u\n", res);
}
return 0;
}最大数字
#include <stdio.h>
#include <stdbool.h>
bool isNonDecr(unsigned int n){
unsigned int left;
while(n){
left = (n/10)%10;
if (left > (n%10)){
return false;
}
n /= 10;
}
return true;
}
int main() {
unsigned int n, res;
scanf("%u",&n);
while(!isNonDecr(n)){
--n;
}
printf("%u",n);
return 0;
}毕达哥拉斯三元组
#include <stdio.h>
unsigned long long pythagoras(unsigned int sum){
// a as short catheti, b as long catheti, c as hypotenuse
unsigned int a,b,c;
for (a = 1; a <= sum/4; ++a){
for (b = a+1; b <= sum/2; ++b){
c = sum-a-b;
if ((a+b > c) && (a*a+b*b == c*c)){
return a*b*c;
}
}
}
}
int main(){
unsigned int n;
scanf("%u",&n);
printf("%llu", pythagoras(n));
return 0;
}竖式乘法
#include <stdio.h>
#include <math.h>
typedef unsigned int uint;
uint digit(uint x){
uint cnt = 0;
if (x == 0){
return 1;
}
while(x){
x /= 10;
++cnt;
}
return cnt;
}
uint getDigital(uint x, uint n){
x /= (uint)pow(10,n-1);
return x%10;
}
int main(){
uint up, down;
scanf("%u %u",&up,&down);
uint ans = up*down, len = digit(ans)+1, downLen = digit(down);
for (uint i = 0; i < len-digit(up); ++i) {
printf(" ");
}
printf("%u\n",up);
printf("x");
for (uint i = 1; i <= len-downLen-1; ++i) {
printf(" ");
}
printf("%u\n",down);
for (uint i = 1; i <= len; ++i) {
printf("-");
}
printf("\n");
uint tmp;
for (uint i = 1; i <= downLen; ++i) {
tmp = getDigital(down,i)*up;
if (i == downLen){
printf("+");
} else {
for (uint j = 1; j <= len-digit(tmp)-i+1; ++j) {
printf(" ");
}
}
printf("%u\n",tmp);
}
for (uint i = 1; i <= len; ++i) {
printf("-");
}
printf("\n");
printf(" %u",ans);
return 0;
}查找数列
#include <stdio.h>
int main(){
int cnt = 1, sum = 0, n, res;
scanf("%d",&n);
while(n-sum > 0){
sum += cnt;
++cnt;
}
sum -= cnt;
res = n-sum == 0 ? cnt : (n-sum-1);
printf("%d",res);
return 0;
}俄罗斯农夫乘法
#include <stdio.h>
int main(){
int multi = 0, a, b;
scanf("%d %d",&a,&b);
while(a){
printf("%d %d\n",a,b);
if (a&1) {
multi += b;
}
a >>= 1;
b <<= 1;
}
printf("%d",multi);
return 0;
}哈沙德数
#include <stdio.h>
int HarshadNumber(int n){
int t = n, s = 0;
while (t) {
s += t%10;
t /= 10;
}
if ((s == 0) || (n%s != 0)) return 0;
if (s == 1) return 1;
return n/s;
}
int main(){
int cnt = 0, n;
scanf("%d",&n);
if (n == 1) cnt = 1;
while ((n != 0) && (n != 1)) {
n = HarshadNumber(n);
if (n) ++cnt;
}
printf("%d",cnt);
return 0;
}基思数
#include <stdio.h>
int arr[8] = {0};
int init(int n){
int cnt = 0;
while (n) {
arr[cnt++] = n%10;
n /= 10;
}
return cnt;
}
void isKeith(int n, int len){
int i = len - 1;
while (arr[i] < n){
int sum = 0;
for (int j = 0; j < len; ++j) {
sum += arr[(i-j+len)%len];
}
arr[i] = sum;
i = (i-1+len)%len;
}
if (arr[i] == n) printf("Yes");
else printf("No");
}
int main() {
int n;
scanf("%d",&n);
isKeith(n,init(n));
return 0;
}二进制表示
#include <stdio.h>
#include <stdbool.h>
void binary(int a){
bool flag = false;
for (int i = 15; i >= 0 ; --i) {
if ((a>>i)&1) {
if (flag) printf("+");
if (i >= 2){
printf("2(");
binary(i);
printf(")");
}
if (i == 1) printf("2");
if (i == 0) printf("2(0)");
flag = true;
}
}
}
int main() {
int a;
scanf("%d",&a);
binary(a);
return 0;
}冰雹数列
#include <stdio.h>
int main() {
int n;
scanf("%d",&n);
while (n != 1) {
printf("%d ",n);
if (n&1) n = 3 * n + 1;
else n /= 2;
}
printf("1");
return 0;
}稀疏矩阵
#include <stdio.h>
int main () {
int raw, col, n, num = 0;
scanf("%d %d", &raw, &col);
for (int i = 0; i < raw; ++i) {
for (int j = 0; j < col; ++j) {
scanf("%d", &n);
if (n) ++num;
}
}
double ratio = (double)num / (raw * col);
if (num == raw || num == col || (ratio - 0.05) <= 1e-9)
printf("Yes\n");
else printf("No\n");
return 0;
}
回文数之和
#include <stdio.h>
#include <stdbool.h>
int dec[10] = {0}, kSys[32] = {0};
bool isPalindrome(int arr[], int cnt){
int head = 0, tail = cnt - 1;
while (head < tail) {
if (arr[head] != arr[tail]) return false;
++head, --tail;
}
return true;
}
bool isBiPalindrome(int n, int k){
int tmp = n, cnt = 0;
while (tmp) {
dec[cnt++] = tmp % 10;
tmp /= 10;
}
if (!isPalindrome(dec, cnt)) return false;
tmp = n, cnt = 0;
while (tmp) {
kSys[cnt++] = tmp % k;
tmp /= k;
}
if (!isPalindrome(kSys, cnt)) return false;
return true;
}
int main() {
int n, k, sum = 0;
scanf("%d %d", &n, &k);
for (int i = 1; i <= n; ++i) {
if (isBiPalindrome(i, k)) sum += i;
}
printf("%d", sum);
return 0;
}前后缀移除
#include <stdio.h>
#include <string.h>
void strLeftStrip(char *str, char *chars) {
int mov = 0;
char *pStr = str;
while (*pStr) {
if (strchr(chars, *pStr)) ++mov;
else break;
++pStr;
}
if (mov) memmove(str - mov, str, strlen(str) + 1);
}
void strRightStrip(char *str, char *chars) {
int len = 0;
char *pStr = str + strlen(str) - 1;
while (pStr >= str) {
if (strchr(chars, *pStr)) ++len;
else break;
--pStr;
}
*(str + strlen(str) - len) = '\0';
}
int main() {
char str1[1000] = "", chars[1000] = "", str2[1000] = "";
scanf("%[^\n] %[^\n]", str1, chars);
memcpy(str2, str1, strlen(str1) + 1);
strLeftStrip(str1, chars);
puts(str1);
strRightStrip(str2, chars);
puts(str2);
strRightStrip(str1, chars);
puts(str1);
return 0;
}字符串后缀
#include <stdio.h>
#include <string.h>
void strEndsWith(char *str, char *suffix) {
int len = strlen(suffix);
char *pStr = str + strlen(str) - len, *pSuffix = suffix;
while (*pSuffix && *pStr) {
if (*pSuffix != *pStr) {
printf("No\n");
return;
}
else ++pSuffix, ++pStr;
}
printf("Yes\n");
}
int main() {
char str[1000] = "", suffix[1000] = "";
scanf("%[^\n] %[^\n]", str, suffix);
strEndsWith(str, suffix);
return 0;
}Atol转换
#include <stdio.h>
#include <limits.h>
int atol(char *str) {
char *pStr = str;
int sgn = 1;
long long tmp = 0;
if (*pStr == '+') ++pStr;
else if (*pStr == '-') sgn = -1, ++pStr;
while (*pStr) {
if (*pStr == ' ') ;
else if ('0' <= *pStr && *pStr <= '9') {
tmp = (*pStr - '0') + tmp * 10;
if ((tmp * sgn) >= INT_MAX) return INT_MAX;
else if ((tmp * sgn) <= INT_MIN) return INT_MIN;
}
else break;
++pStr;
}
return tmp * sgn;
}
int main() {
char str[1000] = "";
scanf("%[^\n]", str);
printf("%d", atol(str));
return 0;
}字符串切片
#include <stdio.h>
#include <string.h>
int t, n, len;
char str[1000];
void strSlice(int begin, int end, int step) {
char slice[1000] = "";
int pos = 0;
if (begin < 0) begin += len;
if (end < 0) end += len;
if (end >= begin && step > 0) {
for (int i = begin; i < end; i += step) {
slice[pos] = str[i];
++pos;
}
} else if (end < begin && step < 0) {
for (int i = begin; i > end; i += step) {
slice[pos] = str[i];
++pos;
}
}
puts(slice);
}
void mode(void) {
len = strlen(str);
int begin, end, step;
switch (n) {
case 3: {
scanf("%d %d %d", &begin, &end, &step);
break;
}
case 2: {
scanf("%d %d", &begin, &end);
step = 1;
break;
}
case 1: {
scanf("%d", &begin);
end = len, step = 1;
break;
}
}
strSlice(begin, end, step);
}
int main() {
scanf("%[^\n] %d", str, &t);
for (int i = 0; i < t; ++i) {
scanf("%d", &n);
mode();
}
return 0;
}分离字符串
#include <stdio.h>
#include <string.h>
void split(char *str, char *sep) {
while (*str) {
char *flag = strstr(str, sep);
if (flag == NULL) break;
char sub[101] = "";
int len = flag - str;
memcpy(sub, str, len);
puts(sub);
memmove(str - len - strlen(sep), str, strlen(str) + 1);
}
puts(str);
}
int main() {
char str[2000] = "", sep[2000] = "";
scanf("%[^\n] %[^\n]", str, sep);
split(str, sep);
return 0;
}Kids A+B
#include <stdio.h>
#include <string.h>
char ans[30] = "";
int strToNum(char *str) {
if(strstr(str, "zero")) return 0;
if(strstr(str, "ten")) return 10;
if(strstr(str, "eleven")) return 11;
if(strstr(str, "twelve")) return 12;
if(strstr(str, "thirteen")) return 13;
if(strstr(str, "fourteen")) return 14;
if(strstr(str, "fifteen")) return 15;
if(strstr(str, "sixteen")) return 16;
if(strstr(str, "seventeen")) return 17;
if(strstr(str, "eighteen")) return 18;
if(strstr(str, "nineteen")) return 19;
int unit = 0, decade = 0;
if(strstr(str, "one")) unit = 1;
if(strstr(str, "two")) unit = 2;
if(strstr(str, "three")) unit = 3;
if(strstr(str, "four")) unit = 4;
if(strstr(str, "five")) unit = 5;
if(strstr(str, "six")) unit = 6;
if(strstr(str, "seven")) unit = 7;
if(strstr(str, "eight")) unit = 8;
if(strstr(str, "nine")) unit = 9;
if(strstr(str, "twenty")) decade = 20;
if(strstr(str, "thirty")) decade = 30;
if(strstr(str, "forty")) decade = 40;
if(strstr(str, "fifty")) decade = 50;
if(strstr(str, "sixty")) decade = 60;
if(strstr(str, "seventy")) decade = 70;
if(strstr(str, "eighty")) decade = 80;
if(strstr(str, "ninety")) decade = 90;
return unit + decade;
}
void numToStr(int n) {
switch (n) {
case 0: {
strcpy(ans, "zero");
char *p = ans;
return;
}
case 11: {
strcpy(ans, "eleven");
char *p = ans;
return;
}
case 12: {
strcpy(ans, "twelve");
char *p = ans;
return;
}
case 13: {
strcpy(ans, "thirteen");
char *p = ans;
return;
}
case 14: {
strcpy(ans, "fourteen");
char *p = ans;
return;
}
case 15: {
strcpy(ans, "fifteen");
char *p = ans;
return;
}
case 16: {
strcpy(ans, "sixteen");
char *p = ans;
return;
}
case 17: {
strcpy(ans, "seventeen");
char *p = ans;
return;
}
case 18: {
strcpy(ans, "eighteen");
char *p = ans;
return;
}
case 19: {
strcpy(ans, "nineteen");
char *p = ans;
return;
}
default:
break;
}
int decade = (n / 10) % 10, unit = n % 10;
switch (decade) {
case 2: {
strcpy(ans, "twenty");
break;
}
case 3: {
strcpy(ans, "thirty");
break;
}
case 4: {
strcpy(ans, "forty");
break;
}
case 5: {
strcpy(ans, "fifty");
break;
}
case 6: {
strcpy(ans, "sixty");
break;
}
case 7: {
strcpy(ans, "seventy");
break;
}
case 8: {
strcpy(ans, "eighty");
break;
}
case 9: {
strcpy(ans, "ninety");
break;
}
default: {
break;
}
}
if (decade && unit) strcat(ans, "-");
switch (unit) {
case 1: {
strcat(ans, "one");
break;
}
case 2: {
strcat(ans, "two");
break;
}
case 3: {
strcat(ans, "three");
break;
}
case 4: {
strcat(ans, "four");
break;
}
case 5: {
strcat(ans, "five");
break;
}
case 6: {
strcat(ans, "six");
break;
}
case 7: {
strcat(ans, "seven");
break;
}
case 8: {
strcat(ans, "eight");
break;
}
case 9: {
strcat(ans, "nine");
break;
}
default: {
break;
}
}
}
int main() {
char a[30] = "", b[30] = "";
scanf("%s %s", a, b);
numToStr(strToNum(a) + strToNum(b));
puts(ans);
return 0;
}时钟A-B
#include <stdio.h>
#include <time.h>
int main(){
struct tm begin = {0}, end = {0};
scanf("%d %d %d", &begin.tm_year, &begin.tm_mon, &begin.tm_mday);
scanf("%d %d %d", &end.tm_year, &end.tm_mon, &end.tm_mday);
begin.tm_year -= 1900, begin.tm_mon -= 1;
end.tm_year -= 1900, end.tm_mon -= 1;
time_t tmBegin = mktime(&begin);
time_t tmEnd = mktime(&end);
// Wrong answer when the difference is negative
printf("%.6lf", difftime(tmBegin, tmEnd));
return 0;
}加密字串
#include <stdio.h>
static int freq[26] = {0};
int main() {
char plain[8000] = "";
int x;
scanf("%s %d", plain, &x);
for (int i = 0; plain[i]; ++i) ++freq[plain[i] - 'a'];
char cipher[8000] = "";
for (int i = 0; plain[i]; ++i) {
if (freq[plain[i] - 'a'] & 1)
cipher[i] = (char) (((plain[i] - 'a' - x) % 26 + 26) % 26 + 'a');
else
cipher[i] = (char) ((plain[i] - 'a' + x) % 26 + 'a');
}
puts(cipher);
return 0;
}
Arduino显示
#include <stdio.h>
static const int digit[10] = {6, 2, 5, 5, 4, 5, 6, 3, 7, 6};
int getUnit(int num) {
int cnt = 0;
do {
cnt += digit[num % 10];
num /= 10;
} while (num);
return cnt;
}
int main() {
int n;
scanf("%d", &n);
n -= 4;
if (n <= 0) printf("0");
else {
int cnt = 0;
for (int i = 0; i <= 1111; ++i) {
for (int j = 0; j <= 1111; ++j) {
if (getUnit(i) + getUnit(j) + getUnit(i + j) == n) ++cnt;
}
}
printf("%d", cnt);
}
return 0;
}三元搜索
#include <stdio.h>
int terSearch(int arr[], int n, int k) {
int left = 0, right = n - 1, mid1 = (n - 1) / 3, mid2 = n - mid1;
while(mid1 != mid2) {
if (k > arr[right] || k < arr[left]) return -1;
if (k == arr[mid1]) return mid1;
if (k == arr[mid2]) return mid2;
if (mid1 == mid2) break;
if (k < arr[mid1]) right = mid1 - 1;
else if (k > arr[mid2]) left = mid2 + 1;
else left = mid1 + 1, right = mid2 - 1;
mid1 = left + (right - left) / 3, mid2 = right - (right - left) / 3;
}
return -1;
}
int main() {
int n, k;
scanf("%d", &n);
int arr[n];
for (int i = 0; i < n; ++i) scanf("%d", &arr[i]);
scanf("%d", &k);
printf("%d in [%d]", k, terSearch(arr, n, k));
return 0;
}循环排序
#include <stdio.h>
void swap(int *a, int *b) {
int tmp = *a;
*a = *b, *b = tmp;
}
void cycleSort(int arr[], int n) {
for (int i = 0; i < n - 1; ++i) {
int item = arr[i], pos = i;
for (int j = i + 1; j < n; ++j) if (arr[j] < item) ++pos;
if (pos == i) continue;
swap(&arr[pos], &item);
while(pos != i) {
pos = i;
for (int j = i + 1; j < n; ++j) if (arr[j] < item) ++pos;
while (item == arr[pos]) ++pos;
swap(&arr[pos], &item);
}
}
}
int main() {
int n;
scanf("%d", &n);
int arr[n];
for (int i = 0; i < n; ++i) scanf("%d", &arr[i]);
cycleSort(arr, n);
for (int i = 0; i < n; ++i) printf("%d ", arr[i]);
return 0;
}中等题
幂数模
#include <stdio.h>
typedef unsigned long long uint64;
uint64 fastPowerMod (uint64 t, uint64 e, uint64 m){
uint64 r = 1;
while (e){
if (e&1){
r = (r*t)%m;
}
t = (t*t)%m;
e >>= 1;
}
return r;
}
int main(){
uint64 a,b,m,r;
scanf("%llu %llu %llu",&a,&b,&m);
r = fastPowerMod(a,b,m);
printf("%llu",r);
return 0;
}倒水
#include <stdio.h>
#include <string.h>
#define INF 0x3f3f3f3f
const int maxSize = 10000;
int distTable[10000][10000];
int queue[10000][2] = {0};
int bfs(int n, int m, int d){
int head = 0, tail = 1;
memset(distTable, 0x3f, sizeof(distTable));
distTable[0][0] = 0;
while(tail != head){
int a = queue[head][0], b = queue[head][1];
if (a == d || b == d) {
return distTable[a][b];
}
head = (head+1)%maxSize;
// full
if(distTable[a][m] == INF) {
distTable[a][m] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = a;
queue[tail][1] = m;
}
if(distTable[n][b] == INF) {
distTable[n][b] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = n;
queue[tail][1] = b;
}
// empty
if(distTable[a][0] == INF) {
distTable[a][0] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = a;
queue[tail][1] = 0;
}
if(distTable[0][b] == INF) {
distTable[0][b] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = 0;
queue[tail][1] = b;
}
// pour
if(a+b < n && distTable[a+b][0] == INF){
distTable[a+b][0] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = a+b;
queue[tail][1] = 0;
}
if(a+b >= n && distTable[n][a+b-n] == INF){
distTable[n][a+b-n] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = n;
queue[tail][1] = a+b-n;
}
if(a+b < m && distTable[0][a+b] == INF){
distTable[0][a+b] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = 0;
queue[tail][1] = a+b;
}
if(a+b >= m && distTable[a+b-m][m] == INF){
distTable[a+b-m][m] = distTable[a][b]+1;
tail = (tail+1)%maxSize;
queue[tail][0] = a+b-m;
queue[tail][1] = m;
}
}
return -1;
}
int main(){
int n,m,d;
scanf("%d %d %d",&n,&m,&d);
printf("%d", bfs(n,m,d));
return 0;
}好数字
#include <stdio.h>
typedef unsigned long long uint64;
const uint64 mod = 1e9+7;
uint64 power(uint64 a, uint64 e){
uint64 r = 1;
while (e){
if (e&1){
r = (r*a)%mod;
}
a = (a*a)%mod;
e >>= 1;
}
return r;
}
int main(){
uint64 n, num;
scanf("%llu",&n);
num = power(4,n/2)*power(5,n-n/2)%mod;
printf("%llu",num);
return 0;
}阶乘倍数
#include <stdio.h>
#include <stdbool.h>
typedef unsigned long long uint64;
uint64 primeFactNum = 0;
uint64 prime[20] = {0}, num[20] = {0};
bool isMulti(uint64 n){
uint64 primeNum, tmp;
for (uint64 i = 1; i <= primeFactNum; ++i) {
primeNum = 0;
tmp = n;
while (tmp) {
primeNum += tmp/prime[i];
tmp /= prime[i];
}
if(primeNum < num[i]) {
return false;
}
}
return true;
}
void solveFact(uint64 k){
for (uint64 i = 2; i*i <= k; ++i) {
if(k%i == 0){
++primeFactNum;
prime[primeFactNum] = i;
while (k%i == 0){
++num[primeFactNum];
k /= i;
}
}
}
if (k > 1){
++primeFactNum;
prime[primeFactNum] = k;
++num[primeFactNum];
}
}
int main(){
uint64 left = 1, right = 1e19, mid, n, k;
scanf("%lld",&k);
solveFact(k);
while(left <= right){
mid = ((right-left)>>1)+left;
if (isMulti(mid)){
right = mid-1;
n = mid;
} else {
left = mid+1;
}
}
printf("%lld",n);
return 0;
}方案数
#include <stdio.h>
int main(){
int cnt = 0, n;
scanf("%d",&n);
for (int i = 1; i*(i+1) <= 2*n; ++i) {
if ((n-i*(i-1)/2)%i == 0){
++cnt;
}
}
printf("%d",cnt);
return 0;
}素数
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
typedef unsigned long long uint64;
uint64 primeNum(uint64 a, uint64 b){
bool isPrime[b+1];
memset(isPrime,1,b+1);
uint64 cnt = 0;
for (uint64 i = 2; i <= b; ++i){
if (isPrime[i]){
for (uint64 j = 2; j*i <= b; ++j){
isPrime[j*i] = false;
}
}
}
for (uint64 i = a; i <= b; ++i){
cnt += isPrime[i];
}
return cnt;
}
int main(){
uint64 a,b,num;
scanf("%llu %llu",&a,&b);
num = primeNum(a,b);
printf("%llu",num);
return 0;
}光线追踪
#include <stdio.h>
unsigned int gcd(unsigned int a, unsigned int b){
if (b == 0) return a;
return gcd(b,a%b);
}
int main(){
unsigned int n,x,l;
scanf("%u %u",&n,&x);
l = 3*(n-gcd(n,x));
printf("%u",l);
return 0;
}运动会
#include <stdio.h>
#include <stdbool.h>
int phiEuler(int n){
int phi[n+1],prime[n+1];
bool isSieved[n+1];
int sum = 0,cnt = 1, comp;
prime[0] = 1;
phi[1] = 1;
for (int i = 2; i < n; ++i){
if (!isSieved[i]){
prime[cnt++] = i;
phi[i] = i-1;
}
for (int j = 1; i*prime[j] <= n; ++j){
comp = i*prime[j];
isSieved[comp] = true;
if (i%prime[j] == 0){
phi[comp] = prime[j]*phi[i];
break;
} else{
phi[comp] = (prime[j]-1)*phi[i];
}
}
}
for (int i = 1; i <= n-1; ++i) {
sum += phi[i];
}
return sum;
}
int main() {
int n, num;
scanf("%d",&n);
num = n == 1 ? 0 : (2*phiEuler(n)+1);
printf("%d",num);
return 0;
}行列式值
Guass消去
#include <stdio.h>
#define MAXSIZE 10
void swap(double arr[MAXSIZE][MAXSIZE], int r1, int r2, int n) {
for (int i = 0; i < n; i++) {
double temp = arr[r1][i];
arr[r1][i] = arr[r2][i];
arr[r2][i] = temp;
}
}
double calDet(double arr[MAXSIZE][MAXSIZE], int n) {
int i, j, k;
double det = 1.0;
for (i = 0; i < n; i++) {
if (arr[i][i] == 0.0) {
for (j = i + 1; j < n; j++) {
if (arr[j][i] != 0.0) {
swap(arr, i, j, n);
det *= -1.0;
break;
}
}
}
if (arr[i][i] == 0.0) {
return 0.0;
}
double v = arr[i][i];
det *= v;
for (j = i; j < n; j++) {
arr[i][j] /= v;
}
for (j = i + 1; j < n; j++) {
double e = arr[j][i];
for (k = i; k < n; k++) {
arr[j][k] -= e * arr[i][k];
}
}
}
return det;
}
int main() {
int n;
scanf("%d", &n);
double arr[MAXSIZE][MAXSIZE];
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
scanf("%lf", &arr[i][j]);
}
}
double det = calDet(arr, n);
printf("%.0lf\n", det);
return 0;
}
按第1行展开（递归）
#include <stdio.h>
#include <stdlib.h>
int** init(int n) {
int** matrix = (int**)malloc(sizeof(int*) * (n + 1));
for(int i = 0; i <= n; i++) {
matrix[i] = (int*)malloc(sizeof(int) * (n + 1));
}
return matrix;
}
int det(int **matrix, int n) {
if (n == 1) return matrix[1][1];
int sum = 0;
int **subMatrix = init(n - 1);
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n - 1; ++j) {
for (int k = 1; k <= n - 1; ++k) {
if (k < i) subMatrix[j][k] = matrix[j + 1][k];
else subMatrix[j][k] = matrix[j + 1][k + 1];
}
}
int sgn = i % 2 == 0 ? -1 : 1;
sum += sgn * matrix[1][i] * det(subMatrix, n - 1);
}
return sum;
}
int main() {
int n;
scanf("%d", &n);
int **matrix = init(n);
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= n; ++j) {
scanf("%d", &matrix[i][j]);
}
}
printf("%d", det(matrix, n));
return 0;
}货运优化
#include <stdio.h>
int main() {
int l3s2[4] = {0, 5, 3, 1};
int n, x1, x2, x3, x4, x5, x6, s2, s1;
while (1) {
scanf("%d %d %d %d %d %d", &x1, &x2, &x3, &x4, &x5, &x6);
if ((x1 + x2 + x3 + x4 + x5 + x6) == 0) break;
n = (x3 + 3) / 4 + x4 + x5 + x6;
s2 = 5 * x4 + l3s2[x3 % 4];
if (x2 > s2) n += (x2 - s2 + 8) / 9;
s1 = 36 * n - 36 * x6 - 25 * x5 - 16 * x4 - 9 * x3 - 4 * x2;
if (x1 > s1) n += (x1 - s1 + 35) / 36;
printf("%d\n",n);
}
return 0;
}素数筛法
#include <stdio.h>
#include <stdbool.h>
#define NUM (int)1e7+1
static bool isSieved[NUM];
static int prime[NUM];
int main() {
int n, k = 0;
scanf("%d", &n);
isSieved[1] = true;
for (int i = 2; i <= n; ++i) {
if (!isSieved[i]) prime[++k] = i;
for (int j = 1; prime[j] * i <= n; ++j) {
isSieved[prime[j] * i] = true;
if (i % prime[j] == 0) break;
}
}
printf("%d", k);
}完美矩阵
#include <stdio.h>
#include <stdbool.h>
#define MAXSIZE 301
int arr[MAXSIZE][MAXSIZE] = {0};
int preSum[MAXSIZE][MAXSIZE] = {0};
void prefix(int n, int m){
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
preSum[i][j] = preSum[i - 1][j] + preSum[i][j - 1]
- preSum[i - 1][j - 1] + arr[i][j];
}
}
}
int getSum(int x1, int x2, int y1, int y2) {
return preSum[x2][y2] - preSum[x1 - 1][y2] - preSum[x2][y1 - 1]
+ preSum[x1 - 1][y1 - 1];
}
bool isPerfect(int x1, int x2, int y1, int y2) {
int outer = getSum(x1, x2, y1, y2), inner;
int len = 2 * (x2 - x1 + y2 - y1);
if ((x2 - x1) == 1 || (y2 - y1) == 1) inner = 0;
else inner = getSum(x1 + 1, x2 - 1, y1 + 1, y2 - 1);
if (inner != 1 && inner != 0 && inner != -1) return false;
if ((outer - inner) != len) return false;
return true;
}
int perfectNum(int n, int m) {
int cnt = 0;
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
for (int k = 1; k + i <= n && k + j <= m; ++k) {
if (arr[i][k + j] == -1 || arr[k + i][j] == -1) break;
if (isPerfect(i, i + k, j, j + k)) {
++cnt;
}
}
}
}
return cnt;
}
int main () {
int n, m;
scanf("%d %d", &n, &m);
for (int i = 1; i <= n; ++i) {
for (int j = 1; j <= m; ++j) {
scanf("%d", &arr[i][j]);
if (arr[i][j] == 0) arr[i][j] = -1;
}
}
prefix(n ,m);
printf("%d", perfectNum(n, m));
return 0;
}删除前后缀
#include <stdio.h>
#include <string.h>
void strRemovePrefix(char *str, char *prefix) {
int cnt = 0;
char *pStr = str, *pPrefix = prefix;
while (*pPrefix && *pStr && *pStr == *pPrefix) {
while (*pPrefix && *pStr && *pStr == *pPrefix)
++pStr, ++pPrefix, ++cnt;
pPrefix = prefix;
}
int len = strlen(prefix);
int mov = (cnt / len) * len;
if (mov) memmove(str - mov, str, strlen(str) + 1);
}
void strRemoveSuffix(char *str, char *suffix) {
int len = strlen(suffix);
char *pStr = str + strlen(str) - len, *pSuffix = suffix;
while (*pSuffix && pStr >= str && *pStr == *pSuffix) {
int cnt = 0;
while (*pSuffix && pStr && *pStr == *pSuffix)
++pStr, ++pSuffix, ++cnt;
if (cnt == len) {
pSuffix = suffix, pStr = pStr - 2 * len;
*(pStr + len) = '\0';
} else break;
}
}
int main() {
char str1[1000] = "", fix[1000] = "", str2[1000] = "";
scanf("%[^\n] %[^\n]", str1, fix);
memcpy(str2, str1, strlen(str1) + 1);
strRemovePrefix(str1, fix);
puts(str1);
strRemoveSuffix(str2, fix);
puts(str2);
return 0;
}元宇宙A+B
#include <stdio.h>
#include <string.h>
const static char decToMeta[37] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
static char c[100] = "", a[100] = "", b[100] = "";
static int C[100] = {0}, A[100] = {0}, B[100] = {0};
int metaToDec(char m) {
if ('0' <= m && m <= '9') return m - '0';
return m - 'A' + 10;
}
void add(void) {
int lenA = strlen(a), lenB = strlen(b);
for (int i = 0; i < lenA; ++i) A[i] = metaToDec(a[lenA - i - 1]);
for (int i = 0; i < lenB; ++i) B[i] = metaToDec(b[lenB - i - 1]);
int carry = 0;
int lenC = lenA > lenB ? lenA : lenB;
for (int i = 0; i < lenC; ++i) {
C[i] = A[i] + B[i] + carry;
carry = C[i] / 36;
C[i] %= 36;
}
if (carry != 0) {
C[lenC] = carry;
++lenC;
}
for (int i = lenC - 1; i >= 0; --i) c[i] = decToMeta[C[lenC - i - 1]];
c[lenC] = '\0';
}
int main() {
scanf("%s %s", a, b);
add();
puts(c);
return 0;
}有效表达式
#include <stdio.h>
int main() {
long long n;
scanf("%lld", &n);
long long cnt = 1;
for (long long i = n + 2; i <= 2 * n; ++i) cnt *= i;
for (long long i = 1; i <= n; ++i) cnt /= i;
printf("%lld", cnt);
return 0;
}长安
#include <stdio.h>
int bx, by, px, py, cnt;
void dfs(int x, int y) {
if ((x == px && y == py) || x > bx || y > by) return;
if (x == bx && y == by) {
++cnt;
return;
}
dfs(x + 1, y);
dfs(x, y + 1);
}
int main() {
while (1) {
fflush(stdin);
scanf("%d %d %d %d", &bx, &by, &px, &py);
if (bx <= 0 || by <= 0 || px <= 0 || py <= 0) break;
cnt = 0;
dfs(1, 1);
printf("%d\n", cnt);
}
return 0;
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