Leetcode Problem 159. Longest Substring with At Most Two Distinct Characters

159. Longest Substring with At Most Two Distinct Characters

Leetcode Solutions

If the string length N is smaller than 3, return N.
Initialize two pointers left = 0 and right = 0 and max_len = 2.
Use a hashmap to keep track of characters and their rightmost positions within the window.
Iterate with the right pointer over the string:
- If the hashmap contains less than 3 distinct characters, add the current character s[right] to the hashmap and move right pointer to the right.
- If the hashmap contains 3 distinct characters, remove the leftmost character from the hashmap and move the left pointer to exclude this character from the window.
- Update max_len with the maximum of its current value and the length of the current window.
Return max_len as the result.

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