How hard is LeetCode 2565. Subsequence With the Minimum Score?

LeetCode 2565. Subsequence With the Minimum Score is rated Hard on LeetCode.

What is the time complexity of LeetCode 2565. Subsequence With the Minimum Score?

The Python solution on this page runs in O(n \times \log n).

What is the space complexity of LeetCode 2565. Subsequence With the Minimum Score?

The Python solution on this page uses O(n) auxiliary space.

What topics does LeetCode 2565. Subsequence With the Minimum Score cover?

LeetCode 2565. Subsequence With the Minimum Score is tagged Two Pointers, String and Binary Search on LeetCode.

Subsequence With the Minimum Score — LeetCode 2565 Python Solution

HardTwo PointersStringBinary Search

Problem: #2565
Pattern: Two Pointers
Reading time: 5 min
Source: leetcode.com

The problem

You are given two strings s and t. You are allowed to remove any number of characters from the string t.

Example

Input: s = "abacaba", t = "bzaa"
Output: 1
Explanation: In this example, we remove the character "z" at index 1 (0-indexed).

Python solution

Python

class Solution:
    def minimumScore(self, s: str, t: str) -> int:
        def check(x):
            for k in range(n):
                i, j = k - 1, k + x
                l = f[i] if i >= 0 else -1
                r = g[j] if j < n else m + 1
                if l < r:
                    return True
            return False

        m, n = len(s), len(t)
        f = [inf] * n
        g = [-1] * n
        i, j = 0, 0
        while i < m and j < n:
            if s[i] == t[j]:
                f[j] = i
                j += 1
            i += 1
        i, j = m - 1, n - 1
        while i >= 0 and j >= 0:
            if s[i] == t[j]:
                g[j] = i
                j -= 1
            i -= 1

        return bisect_left(range(n + 1), True, key=check)

Complexity

Measure	Complexity
Time	O(n \times \log n)
Space	O(n) auxiliary

Pattern: Two Pointers

Use the order already in the input to discard half the search space at every step. LeetCode 2565. Subsequence With the Minimum Score is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Two Pointers.

The two pointers guide has the Python template for the pattern and the 201 LeetCode problems that use it.

Frequently asked questions

How hard is LeetCode 2565. Subsequence With the Minimum Score?: LeetCode 2565. Subsequence With the Minimum Score is rated Hard on LeetCode.
What is the time complexity of LeetCode 2565. Subsequence With the Minimum Score?: The Python solution on this page runs in O(n \times \log n).
What is the space complexity of LeetCode 2565. Subsequence With the Minimum Score?: The Python solution on this page uses O(n) auxiliary space.
What topics does LeetCode 2565. Subsequence With the Minimum Score cover?: LeetCode 2565. Subsequence With the Minimum Score is tagged Two Pointers, String and Binary Search on LeetCode.