LeetCode-in-Java

1208. Get Equal Substrings Within Budget

Medium

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 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.

Example 1:

Input: s = “abcd”, t = “bcdf”, maxCost = 3

Output: 3

Explanation: “abc” of s can change to “bcd”. That costs 3, so the maximum length is 3.

Example 2:

Input: s = “abcd”, t = “cdef”, maxCost = 3

Output: 1

Explanation: Each character in s costs 2 to change to character in t, so the maximum length is 1.

Example 3:

Input: s = “abcd”, t = “acde”, maxCost = 0

Output: 1

Explanation: You cannot make any change, so the maximum length is 1.

Constraints:

• 1 <= s.length <= 105
• t.length == s.length
• 0 <= maxCost <= 106
• s and t consist of only lowercase English letters.

Solution

public class Solution {
    public int equalSubstring(String s, String t, int maxCost) {
        int start = 0;
        int end = 0;
        int currCost = 0;
        int maxLength = Integer.MIN_VALUE;
        while (end < s.length()) {
            currCost += Math.abs(s.charAt(end) - t.charAt(end));
            while (currCost > maxCost) {
                currCost -= Math.abs(s.charAt(start) - t.charAt(start));
                start++;
            }
            if (end - start + 1 > maxLength) {
                maxLength = Math.max(end - start + 1, maxLength);
            }
            end++;
        }
        return maxLength;
    }
}

This site is open source. Improve this page.