UVa11041 Triangle Counting 数三角形 题解

#include <stdio.h>int main(){    int n;    while (scanf("%d", &n) == 1)    {        if (n < 3)        {            break;        }        long long ret = 0;        int a = n / 2;        int b = (n - 1) / 2;                ret += (long long)(a - 1) * a * (2 * a - 1) / 6;        ret += (long long)b * (b + 1) * (b - 1) / 3;        printf("%lld\n", ret);    }    return 0;}