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.
Solution:
class Solution {
public int equalSubstring(String s, String t, int maxCost) {
int n = s.length();
int max = 0;
int curLen = 0;
int left = 0;
int right = 0;
int curCost = maxCost;
while (right < n) {
char a = s.charAt(right);
char b = t.charAt(right);
if (a == b) {
curLen ++;
} else {
while (left < right && curCost - Math.abs(a - b) < 0) {
curCost += Math.abs(s.charAt(left) - t.charAt(left));
left ++;
curLen --;
}
if (curCost - Math.abs(a - b) >= 0) {
// System.out.println(a + ", " + b + ", " + Math.abs(a - b));
curCost -= Math.abs(a - b);
curLen ++;
} else {
left ++;
curLen = 0;
curCost = maxCost;
}
}
max = Math.max(curLen, max);
right ++;
}
return max;
}
}