- Difficulty: Hard
- Tags: LeetCode, Hard, Two Pointers, String, Binary Search, leetcode-2565, Dynamic Programming, O(n), DP
Problem
You are given two strings s
and t
.
You are allowed to remove any number of characters from the string t
.
The score of the string is 0
if no characters are removed from the string t
, otherwise:
- Let
left
be the minimum index among all removed characters. - Let
right
be the maximum index among all removed characters.
Then the score of the string is right - left + 1
.
Return the minimum possible score to make t
a subsequence of s
.
A subsequence of a string is a new string that is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (i.e., "ace"
is a subsequence of "abcde"
while "aec"
is not).
Example 1:
Input: s = "abacaba", t = "bzaa" Output: 1 Explanation: In this example, we remove the character "z" at index 1 (0-indexed). The string t becomes "baa" which is a subsequence of the string "abacaba" and the score is 1 - 1 + 1 = 1. It can be proven that 1 is the minimum score that we can achieve.
Example 2:
Input: s = "cde", t = "xyz" Output: 3 Explanation: In this example, we remove characters "x", "y" and "z" at indices 0, 1, and 2 (0-indexed). The string t becomes "" which is a subsequence of the string "cde" and the score is 2 - 0 + 1 = 3. It can be proven that 3 is the minimum score that we can achieve.
Constraints:
1 <= s.length, t.length <= 105
s
andt
consist of only lowercase English letters.