Sliding window program decomposition

class Solution {     public int equalSubstring(String s, String t, int maxCost) {         int left = 0, right =0;         int sum = 0;         int res = 0; // construct window         while (right < s.length()) {             sum += Math.abs(s.charAt(right) - t.charAt(right));             right++; // The window construction is completed, and the window size should be adjusted according to the current window             while (sum > maxCost) {                 sum -= Math.abs(s.charAt(left) - t.charAt(left));                 left++;             } // Record the size of the window at this time             res = Math.max(res, right -left);         }         return res;     } }