A30678.求阶乘的和 题解

#include <bits/stdc++.h>
using namespace std;
int n,ans,cnt;
int main(){
    cin>>n;
    for (int i=1;i<=n;i++){
        cnt=1;
        for (int j=2;j<=i;j++){
            cnt*=j;
        }
        ans+=cnt;
    }
    cout<<ans;
    return 0;
}