<p>We are given <code>n</code> different types of <code>stickers</code>. Each sticker has a lowercase English word on it.</p>

<p>You would like to spell out the given string <code>target</code> by cutting individual letters from your collection of stickers and rearranging them. You can use each sticker more than once if you want, and you have infinite quantities of each sticker.</p>

<p>Return <em>the minimum number of stickers that you need to spell out </em><code>target</code>. If the task is impossible, return <code>-1</code>.</p>

<p><strong>Note:</strong> In all test cases, all words were chosen randomly from the <code>1000</code> most common US English words, and <code>target</code> was chosen as a concatenation of two random words.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> stickers = [&quot;with&quot;,&quot;example&quot;,&quot;science&quot;], target = &quot;thehat&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong>
We can use 2 &quot;with&quot; stickers, and 1 &quot;example&quot; sticker.
After cutting and rearrange the letters of those stickers, we can form the target &quot;thehat&quot;.
Also, this is the minimum number of stickers necessary to form the target string.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> stickers = [&quot;notice&quot;,&quot;possible&quot;], target = &quot;basicbasic&quot;
<strong>Output:</strong> -1
Explanation:
We cannot form the target &quot;basicbasic&quot; from cutting letters from the given stickers.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == stickers.length</code></li>
	<li><code>1 &lt;= n &lt;= 50</code></li>
	<li><code>1 &lt;= stickers[i].length &lt;= 10</code></li>
	<li><code>1 &lt;= target.length &lt;= 15</code></li>
	<li><code>stickers[i]</code> and <code>target</code> consist of lowercase English letters.</li>
</ul>

class Solution {
public:
int dp[1<<15];
int n,m;
int fun(int mask,vector<string>&stickers,string &target){
    if(mask==(1<<m)-1){
        return 0;
    }
    if(dp[mask]!=-1)return dp[mask];
    int ans=1e9;
    for(int i=0;i<n;i++){
        vector<int>cnt(26,0);
        for(int j=0;j<stickers[i].size();j++){
               cnt[stickers[i][j]-'a']++;
        }
        int newmask=0;
        for(int j=0;j<m;j++){
            if(!((1<<j)&mask)){
                if(cnt[target[j]-'a']>0){
                    cnt[target[j]-'a']--;
                    newmask|=(1<<j);
                }
            }
        }
        if(newmask!=0)ans=min(ans,1+fun(mask|newmask,stickers,target));

    }
   return dp[mask]=ans;
}
    int minStickers(vector<string>& stickers, string target) {
       n=stickers.size();
       m=target.size();
        memset(dp,-1,sizeof(dp));
        int ans=fun(0,stickers,target);
        if(ans>=1e9)return -1;
        return ans;
    }
};
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