Longest Balanced Substring With One Swap
Given a binary string s, perform at most one swap between any two characters, then select a substring with an equal number of '0's and '1's. Return the maximum length of such a balanced substring.
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Early May, 2026
Mid-level
You are given a binary string s consisting only of characters '0' and '1'. A string is balanced if it contains an equal number of '0's and '1's. You can perform at most one swap between any two characters in s. Then, you select a balanced from s. Return an integer representing the maximum length of the balanced substring you can select. Example 1: Input: s = "100001" Output: 4 Explanation: Swap "100001". The string becomes "101000". Select the substring "101000", which is balanced because it has two '0's and two '1's. Example 2: Input: s = "111" Output: 0 Explanation: Choose not to perform any swaps. Select the empty substring, which is balanced because it has zero '0's and zero '1's.
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