<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 n=s.size();
        unordered_map<char,int>mask;
        mask['0']=1,mask['1']=2,mask['2']=4,mask['3']=8,mask['4']=16,mask['5']=32,mask['6']=64,mask['7']=128,mask['8']=256,mask['9']=512;
        unordered_map<int,int>mpp;
        mpp[0]=-1;
        int xr=0,len=1;
        for(int i=0; i<n; i++){
            xr^=mask[s[i]];
            if(mpp.find(xr)!=mpp.end()){
                len=max(len,i-mpp[xr]);
            }
            for(auto [ch,bit]:mask){
                int oddxr=xr^bit;
                if(mpp.find(oddxr)!=mpp.end()){
                    len=max(len,i-mpp[oddxr]);
                }
            }
            if(mpp.find(xr)==mpp.end()){
                mpp[xr]=i;
            }
        }
        return len;
    }
};
13800