SP1026 FAVDICE - Favorite Dice 数学期望

Code:

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
#define maxn 1009
double dp[maxn];
int main(){
    int n,t;
    scanf("%d",&t);
    while(t--){
        scanf("%d",&n);
        dp[n]=0.0;
        for(int i=n-1;i>=0;--i) {
            dp[i]=(double)(dp[i+1]*(n-i)/n+1)*n/(n-i); 
        }
        printf("%.2lf\n",dp[0]);
    }
    return 0;
}