Problem Description
You are given two strings s and t of the same length and an integer maxCost. You want to change s to t. Changing the ith character of s to the ith character of t costs |s[i] - t[i]| (i.e., the absolute difference between the ASCII values of the characters). Return the maximum length of a substring of s that can be changed to be the same as the corresponding substring of t with a cost less than or equal to maxCost. If there is no substring from s that can be changed to its corresponding substring from t, return 0.
Key Insights
- The cost of changing characters can be calculated using the absolute difference of their ASCII values.
- The problem can be solved using a sliding window approach to maintain a substring where the cumulative cost does not exceed
maxCost. - The length of the substring is determined by the current window, which expands and contracts based on the cost incurred.
Space and Time Complexity
Time Complexity: O(n)
Space Complexity: O(1)
Solution
The solution involves utilizing a sliding window technique to efficiently determine the maximum length of valid substrings. The algorithm maintains two pointers to represent the current window in the string. As we iterate through the string, we calculate the cost of changing characters from s to t. If the cumulative cost exceeds maxCost, we increment the start pointer to reduce the window size until the cost is within the allowed budget. Throughout this process, we keep track of the maximum length of valid substrings encountered.