<p>The <strong>variance</strong> of a string is defined as the largest difference between the number of occurrences of <strong>any</strong> <code>2</code> characters present in the string. Note the two characters may or may not be the same.</p>

<p>Given a string <code>s</code> consisting of lowercase English letters only, return <em>the <strong>largest variance</strong> possible among all <strong>substrings</strong> of</em> <code>s</code>.</p>

<p>A <strong>substring</strong> is a contiguous sequence of characters within a string.</p>

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

<pre>
<strong>Input:</strong> s = &quot;aababbb&quot;
<strong>Output:</strong> 3
<strong>Explanation:</strong>
All possible variances along with their respective substrings are listed below:
- Variance 0 for substrings &quot;a&quot;, &quot;aa&quot;, &quot;ab&quot;, &quot;abab&quot;, &quot;aababb&quot;, &quot;ba&quot;, &quot;b&quot;, &quot;bb&quot;, and &quot;bbb&quot;.
- Variance 1 for substrings &quot;aab&quot;, &quot;aba&quot;, &quot;abb&quot;, &quot;aabab&quot;, &quot;ababb&quot;, &quot;aababbb&quot;, and &quot;bab&quot;.
- Variance 2 for substrings &quot;aaba&quot;, &quot;ababbb&quot;, &quot;abbb&quot;, and &quot;babb&quot;.
- Variance 3 for substring &quot;babbb&quot;.
Since the largest possible variance is 3, we return it.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;abcde&quot;
<strong>Output:</strong> 0
<strong>Explanation:</strong>
No letter occurs more than once in s, so the variance of every substring is 0.
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
	<li><code>s</code> consists of lowercase English letters.</li>
</ul>

class Solution:
    def largestVariance(self, s: str) -> int:
        # def getvar(a, b):
        #     max_var = curr_var = 0
        #     has_b = start_b = False
        #     for c in s:
        #         if c == a:
        #             curr_var += 1
        #         elif c == b:
        #             has_b = True
        #             if start_b and curr_var >= 0:
        #                 start_b = False
        #             elif curr_var - 1 < 0:
        #                 start_b = True
        #                 curr_var = -1
        #             else:
        #                 curr_var -= 1
        #         if has_b:
        #             max_var = max(max_var, curr_var)
        #     return max_var

        # unique = set(s)
        # ans = 0
        # for a in unique:
        #     for b in unique:
        #         if a != b:
        #             ans = max(ans, getvar(a, b))
        # return ans
        unique = set(s)
        ans = 0
        for a in unique:
            for b in unique:
                if a != b:
                    a_without_b = 0
                    var_with_b=float("-inf")
                    for c in s:
                        if c==a:
                            a_without_b+=1
                            var_with_b+=1
                        elif c==b:
                            var_with_b = max(a_without_b-1,var_with_b-1)
                            a_without_b=0
                        ans=max(ans, var_with_b)
        return ans

4191