<p>You are given a string <code>s</code>. An <strong>awesome</strong> substring is a non-empty substring of <code>s</code> such that we can make any number of swaps in order to make it a palindrome.</p>

<p>Return <em>the length of the maximum length <strong>awesome substring</strong> of</em> <code>s</code>.</p>

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

<pre>
<strong>Input:</strong> s = &quot;3242415&quot;
<strong>Output:</strong> 5
<strong>Explanation:</strong> &quot;24241&quot; is the longest awesome substring, we can form the palindrome &quot;24142&quot; with some swaps.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;12345678&quot;
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;213123&quot;
<strong>Output:</strong> 6
<strong>Explanation:</strong> &quot;213123&quot; is the longest awesome substring, we can form the palindrome &quot;231132&quot; with some swaps.
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>5</sup></code></li>
	<li><code>s</code> consists only of digits.</li>
</ul>

class Solution {
public:
   int longestAwesome(string &s) {
    
    
    int pre=0^(1<<(s[0]-'0'));
    unordered_map<int,int>mp;
    mp[pre]=0;
    mp[0]=-1;
    int ans=1;
    for(int i=1;i<s.size();i++){
        pre^=(1<<(s[i]-'0'));
        auto it=mp.find(pre);
        if(it==mp.end())
        {
            mp[pre]=i;
        }
        else
        {
            ans=max(ans,i-it->second);
        }
       
        for(int j=0;j<=9;j++)
        {
            int temp=pre^(1<<j);
            
            auto it2=mp.find(temp);
            if(it2!=mp.end())
            {
                ans=max(ans,i-it2->second);
            }
           
        }
    }
   
    return ans;
}
};
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