<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 n=s1.length();
        int m=s2.length();
        for(int i=0;i<n;i++){
            mp[s1[i]]++;
            // cout<<s1[i]<<" ";
        }
        // for(auto i:mp) cout<<i.first<<" "<<i.second<<" ";
        // cout<<mp.size()<<endl;
        int i=0;
        int j=0;
        while(i<s2.length() and j<s2.length()){
                // for(auto j:mp) cout<<j.first<<"- "<<j.second<<"- "<<endl;
            if(mp.find(s2[i])!=mp.end()){ 
                // cout<<
                unordered_map<char,int>mp2=mp;
                // for(auto k:mp2){
                //     cout<<k.first<<" "<<k.second<<" ";
                // }
                // cout<<endl;
                // cout<<"->"<<mp2.size()<<endl;
                // cout<<s2[i]<<endl;
                j=i;
                // cout<<j<<endl;
                while(mp2[s2[j]]>0){
                    mp2[s2[j]]--;
                    // cout<<mp2[s2[j]]<<"-"<<s2[j]<<endl;
                    if(mp2[s2[j]]==0) mp2.erase(s2[j]);
                    // cout<<mp2.size();
                    if(mp2.size()==0) return true;
                    j++;
                }
            }
            i++;
        }
        return false;
    }
};
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