#include<cstdio> #include<cstring> #include<algorithm> #include<iostream> using namespace std; double a,sum,ans=5040; int main() { for(int i=1;i<=7;++i){ cin>>a; sum+=a; ans*=a; } for(int i=0;i<=5;++i) ans/=(sum-i); printf("%.3f",ans); return 0; }
原文：https://www.cnblogs.com/nnezgy/p/11594462.html