<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 check(vector<int>v,string s2){
         vector<int>v2(26,0);
        for(int i=0;i<s2.length();i++){
            int ch=s2[i] - 'a';
            v2[ch]++;
        }
        for(int i=0;i<26;i++){
            if(v[i]!=v2[i]){
                return false;
            }
        }
        return true;
    }
    bool checkInclusion(string s1, string s2) {
        if(s1.length()>s2.length()){
            return false;
        }
        vector<int>v(26,0);
        for(int i=0;i<s1.length();i++){
            int ch=s1[i] - 'a';
            v[ch]++;
        }
        int window=s1.length();
        for(int i=0;i<s2.length()-window+1;i++){
                string temp=s2.substr(i,window);
                if(check(v,temp)){
                    return true;
                }
        }
        return false;
    }
};
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