Hdu-2156-分数矩阵 [水题]

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题目传送门

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只需要求上三角矩阵的和再乘2减去n。

#include <algorithm>#include <iostream>#include <cstdlib>#include <cstring>#include <cstdio>#include <cmath>#include <stack>using namespace std;int main(void){    int n;    while (scanf("%d", &n))    {        if (n==0)            break;        double s=0,ss=0;        for (int i = 1; i <= n; i++)        {            ss = ss+1.0/i;            s = s + ss;        }        printf("%.2f\n",s*2-n);    }    return 0;}