<p>The set <code>[1, 2, 3, ...,&nbsp;n]</code> contains a total of <code>n!</code> unique permutations.</p>

<p>By listing and labeling all of the permutations in order, we get the following sequence for <code>n = 3</code>:</p>

<ol>
	<li><code>&quot;123&quot;</code></li>
	<li><code>&quot;132&quot;</code></li>
	<li><code>&quot;213&quot;</code></li>
	<li><code>&quot;231&quot;</code></li>
	<li><code>&quot;312&quot;</code></li>
	<li><code>&quot;321&quot;</code></li>
</ol>

<p>Given <code>n</code> and <code>k</code>, return the <code>k<sup>th</sup></code> permutation sequence.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> n = 3, k = 3
<strong>Output:</strong> "213"
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> n = 4, k = 9
<strong>Output:</strong> "2314"
</pre><p><strong class="example">Example 3:</strong></p>
<pre><strong>Input:</strong> n = 3, k = 1
<strong>Output:</strong> "123"
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= n &lt;= 9</code></li>
	<li><code>1 &lt;= k &lt;= n!</code></li>
</ul>

class Solution {
public:

    int count = 0;
    string ans  = "",temp = "";
    int check;

    string getPermutation(int n, int k) {
        check = pow(2,n)-1;
        find(n,k,0);
        return ans;
    }

    void find(int n,int k,int mask){
        if(mask==check){
            count++;
            if(k==count) ans = temp;
            return;
        }
        for(int i = 0;i<n;i++){
            if(ans!="") break;
            if(((mask>>i)&1)==1) continue;
            else{
                mask+=(1<<i);
                temp+=(i+1+'0');
                find(n,k,mask);
                temp.pop_back();
                mask-=(1<<i);
            }
        }
        return ;
    }

};
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