题解

#include<bits/stdc++.h>
using namespace std;
int n,res=0;
int main()
{
    cin >> n;
    int i,j,k;
    for(k=0;k<=n;k=k+3)
    {
    	i=(4*k)/3-n;
    	j=2*n-(7*k)/3;
    	if(5*i+3*j+k/3==n&&i>=0&&j>=0) 
    		res++;
	}
    cout << res << endl;
}

燃烧吧！CPU！