<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) {
        vector<int>mp(26);
        for(auto s:s1){
            mp[s-'a']++;
        }
        string currWindow="";
        for(int i=0;i<s2.size();i++){
            if(mp[s2[i]-'a']>0){
                mp[s2[i]-'a']--;
                currWindow+=s2[i];
                if(currWindow.length()==s1.length()){
                    return true;
                }
            }else{
                if(currWindow.length()>0){
                     bool trg=true;
                        for(int j=0;j<currWindow.length();j++){
                            if(currWindow[j]==s2[i]){
                                currWindow=currWindow.substr(j+1);
                                currWindow+=s2[i];
                                trg=false;
                                break;
                            }
                            mp[currWindow[j]-'a']++;
                        }
                        if(trg){
                            currWindow="";
                        }
                    }
                }
        }
        return false;
    }
};
17409