<p>Given two strings <code>s1</code> and <code>s2</code>, return <code>true</code><em> if </em><code>s2</code><em> contains a permutation of </em><code>s1</code><em>, or </em><code>false</code><em> otherwise</em>.</p>

<p>In other words, return <code>true</code> if one of <code>s1</code>&#39;s permutations is the substring of <code>s2</code>.</p>

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

<pre>
<strong>Input:</strong> s1 = &quot;ab&quot;, s2 = &quot;eidbaooo&quot;
<strong>Output:</strong> true
<strong>Explanation:</strong> s2 contains one permutation of s1 (&quot;ba&quot;).
</pre>

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

<pre>
<strong>Input:</strong> s1 = &quot;ab&quot;, s2 = &quot;eidboaoo&quot;
<strong>Output:</strong> false
</pre>

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

<ul>
	<li><code>1 &lt;= s1.length, s2.length &lt;= 10<sup>4</sup></code></li>
	<li><code>s1</code> and <code>s2</code> consist of lowercase English letters.</li>
</ul>

class Solution {
public:
    bool checkInclusion(string s1, string s2) {
        unordered_map<char,int> mp;
        int i=0;
        int window=s1.size();
        //int j=1+window;
        bool flag=false;
        for(auto i:s1)
        {
            mp[i]++;
        }
        while(i<s2.size())
        {
            if(mp.find(s2[i])!=mp.end())
            {
                flag=true;
                int j=i;
                int cnt=0;
                unordered_map<char,int> temp=mp;
                while(j<i+window)
                {
                    if(temp[s2[j]]>0)
                    {
                        temp[s2[j]]--;
                        cnt++;
                    }
                    else
                    {
                        break;
                    }
                    j++;
                }
                if(cnt==window)
                {
                    return true;
                }
                else 
                {
                    flag=false;
                    j=j-1;
                }
            }
            i++;
        }
        return flag;
    }
};
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