五个五个相同,再考虑剩下的。
#include<iostream> #include<string.h> using namespace std; long long find(long long n) { long long count= 0; while(n > 0) { count += n / 5; n = n / 5; } return count; } int main() { long long n,i,sum=0,t; while(cin>>n) { sum=0; t=n%5+1; n=n-t; for(i=0;i<=n;i+=5) { sum+=find(i)*5; } if(t!=0) sum+=find(n+t)*t; cout<<sum<<endl; } return 0; }
///新手大神勿喷