#include <stdio.h>
#include <time.h>

int main() {
    long timea, timeb, timec;//clock_t timea;
    long a = 1LL, b = 100000000LL;
    long long result1 = 0LL, result2 = 0LL;  

    timea = clock();    
    for (long long i = a; i <= b; i++) {
        result1 += i;    
    }
    timeb = clock();    
    printf("累加结果: %lld, 所用时间: %lf 毫秒\n", result1, (double)(timeb - timea) / CLOCKS_PER_SEC * 1000);

    result2 = (a + b) * (b - a + 1) / 2;
    timec = clock();    
    printf("高斯结果: %lld, 所用时间: %lf 毫秒\n", result2, (double)(timec - timeb) / CLOCKS_PER_SEC * 1000);    
 
    return 0; 
}