DFS BestCoder Round #49 ($) 1001 Untitled

题目传送门

 /*
     DFS：从大到小取模，因为对比自己大的数取模没意义，可以剪枝。但是我从小到大也过了，可能没啥大数据
 */
 /************************************************
 Author        :Running_Time
 Created Time  :2015-8-1 18:57:52
 File Name     :A.cpp
 *************************************************/

 #include <cstdio>
 #include <algorithm>
 #include <iostream>
 #include <sstream>
 #include <cstring>
 #include <cmath>
 #include <string>
 #include <vector>
 #include <queue>
 #include <deque>
 #include <stack>
 #include <list>
 #include <map>
 #include <set>
 #include <bitset>
 #include <cstdlib>
 #include <ctime>
 using namespace std;

 typedef long long ll;
 const int MAXN = ;
 const int INF = 0x3f3f3f3f;
 const int MOD = 1e9 + ;
 int a[MAXN];
 bool vis[MAXN];
 int n, ans;

 bool cmp(int x, int y)  {
     return x > y;
 }

 void DFS(int now, int step) {
     for (int i=; i<=n; ++i)    {
         if (vis[i] || now < a[i]) continue;
         if (now % a[i] == )    {
             ans = min (ans, step + );  return ;
         }
         vis[i] = true;  DFS (now % a[i], step + ); vis[i] = false;
     }
 }

 int main(void)    {       //HDOJ 5339 Untitled
     int T;  scanf ("%d", &T);
     while (T--) {
         int x;   scanf ("%d%d", &n, &x);
         for (int i=; i<=n; ++i)    scanf ("%d", &a[i]);
         sort (a+, a++n, cmp);
         if (x < a[n])   {
             puts ("-1");    continue;
         }
         memset (vis, false, sizeof (vis));
         ans = INF;  DFS (x, );
         if (ans == INF) puts ("-1");
         else    printf ("%d\n", ans);
     }

     return ;
 }