html計算1到n的和,計算1-n的和的兩種方法，與計算時間

#include

#include

#include

int add1(long n) {

long i, sum = 0;

for (i = 0; i <= n; i++) {

sum+=i;

}

return sum;

}

void AddTime1(long n) {

clock_t t;

t = clock();

long sum;

sum = add1(n);

t = clock() - t;

printf("方法一：\n");

printf("用時為：%lf\n", ((float)t)/CLOCKS_PER_SEC);

printf("結果為：從1-%ld的和是%ld\n", n, sum);

}

int add2(long n) {

long sum;

return  n * (n + 1)/ 2;

}

void AddTime2(long n) {

clock_t t;

t = clock();

long sum;

sum = add2(n);

t = clock() - t;

printf("方法二：\n");

printf("用時為：%lf\n", ((float)t) / CLOCKS_PER_SEC);

printf("結果為：從1-%ld的和是%ld\n", n, sum);

}

int main() {

int n;

printf("n(大于1000000)：");

scanf_s("%d", &n);

if (n < 1000000)return 0;

AddTime1(n);

AddTime2(n);

return 1;

}