Character Replacement Solution

Explanation: Step-by-step: with input s = "ABBBCC" and k = 2, we initialize two pointers at the start of the string. We then iterate over the string, expanding the window to the right. When we encounter a character that is different from the character at the left pointer, we increment the count of different characters. If the count exceeds k, we move the left pointer to the right until the count is less than or equal to k. The maximum length of the substring with at most k different characters is then the maximum length of the window. In this case, the longest substring with at most 2 different characters is 'BBB' and 'CCC' which has a length of 3.

Explanation: Step-by-step: with input s = "ABC" and k = 1, we initialize two pointers at the start of the string. We then iterate over the string, expanding the window to the right. When we encounter a character that is different from the character at the left pointer, we increment the count of different characters. If the count exceeds k, we move the left pointer to the right until the count is less than or equal to k. The maximum length of the substring with at most k different characters is then the maximum length of the window. In this case, the longest substring with at most 1 different character is 'A' or 'B' or 'C' which has a length of 1.