leetcode 1208. Get Equal Substrings Within Budget

Seawolf

You are given two strings s and t of the same length. You want to change s to t. Changing the i-th character of s to i-th character of t costs |s[i] - t[i]| that is, the absolute difference between the ASCII values of the characters.

You are also given an integer maxCost.

Return the maximum length of a substring of s that can be changed to be the same as the corresponding substring of twith 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 charactor in t, so the maximum length is 1.
Example 3:

Input: s = "abcd", t = "acde", maxCost = 0
Output: 1
Explanation: You can't make any change, so the maximum length is 1.
 

Constraints:

1 <= s.length, t.length <= 10^5
0 <= maxCost <= 10^6
s and t only contain lower case English letters.

sliding window!

class Solution {
    public int equalSubstring(String s, String t, int k) {
        int i = 0, j;
        int n = s.length();
        for(j = 0; j<n ; j++){
            k -= Math.abs(s.charAt(j) - t.charAt(j));
            
            if(k < 0) k+= Math.abs(s.charAt(i) - t.charAt(i++));
        }
        
        return j - i;
    }
}