Educational Codeforces Round 34 div2 Hungry Student Problem 简单dfs

Hungry Student Problem

Ivan’s classes at the university have just finished, and now he wants to go to the local CFK cafe and eat some fried chicken.

CFK sells chicken chunks in small and large portions. A small portion contains 3 chunks; a large one — 7 chunks. Ivan wants to eat exactly x chunks. Now he wonders whether he can buy exactly this amount of chicken.

Formally, Ivan wants to know if he can choose two non-negative integers a and b in such a way that a small portions and b large ones contain exactly x chunks.

Help Ivan to answer this question for several values of x!

Input
The first line contains one integer n (1 ≤ n ≤ 100) — the number of testcases.

The i-th of the following n lines contains one integer xi (1 ≤ xi ≤ 100) — the number of chicken chunks Ivan wants to eat.

Output
Print n lines, in i-th line output YES if Ivan can buy exactly xi chunks. Otherwise, print NO.

Example
input
2
6
5
output
YES
NO
Note
In the first example Ivan can buy two small portions.

In the second example Ivan cannot buy exactly 5 chunks, since one small portion is not enough, but two small portions or one large is too much.

#include<cstdio>#include<iostream>using namespace std;bool dfs(int n){   if(n<=0)return 0;    if(n%7==0||n%3==0||n%10==0&&n){ return 1;}    else    {    dfs(n-3);    dfs(n-7);    }}int main(){    int t;    scanf("%d",&t);    while(t--)    {        int n;        scanf("%d",&n);        if(dfs(n)) cout<<"YES"<<endl;        else            cout<<"NO"<<endl;       }}