<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 now = 0;
        unordered_set<int> check;
        unordered_map<int, int> mp;
        check.insert(0);

        int ans = 1;

        for(int i = 0;i < s.size();i++) {
            now = now ^ (1 << (s[i] - '0'));
            if(check.count(now) == 0) {
                check.insert(now);
                mp[now] = i + 1;
            }
            
            ans = max(ans, i - mp[now] + 1);

            for(int j = 0;j < 10;j++) {
                if (check.count(now ^ (1 << j)) == 0) {
                    continue;
                }
                int tmp = mp[now ^ (1 << j)];
                ans = max(ans, i - tmp + 1);
            }
            //cout<<ans<<endl;
        }

        return ans;
    }
};
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