Today I have done leetcode's May LeetCoding Challenge with cpp.

May LeetCoding Challenge 28

Description

Get Equal Substrings Within Budget

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

class Solution {
public:
  int equalSubstring(string s, string t, int maxCost) {
    int begin = 0;
    int end = 0;
    int answer = 0;
    int cost = 0;
    while(end < s.length()) {
      cost += abs(s[end] - t[end]);
      while(cost > maxCost && begin <= end) {
        cost -= abs(s[begin] - t[begin]);
        begin += 1;
      }
      answer = max(answer, end - begin + 1);
      end += 1;
    }
    return answer;
  }
};