poj 1775 Sum of Factorials dfs

水~但是很阴险。

#include <stdio.h>

int n,m,vis[15];
int ar[]={1,1,2,6,24,120,720,5040,40320,362880};

int dfs(int i,int data)
{
    int j;
    if(data>n)return 0;
    if(data==n)return 1;
    for (j=i;j<=9;j++)
    {
        if(!vis[j])
        {
            vis[j]=1;
            if(dfs(j+1,data+ar[j]))return 1;
            vis[j]=0;
        }
    }
    return 0;
}

int main()
{
    int i;
    while (scanf("%d",&n)!=EOF)
    {
        if(n<0)break;
        if(n==0)
        {
            printf("NO\n");continue;
        }
        for(i=0;i<=10;i++)vis[i]=0;
        if(dfs(0,0))printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}