Delete Operation for Two Strings — LeetCode 583 Python Solution

The problem

Given two strings word1 and word2, return the minimum number of steps required to make word1 and word2 the same. In one step, you can delete exactly one character in either string.

Example

Input

word1 = "sea", word2 = "eat"

Output

2

Explanation

You need one step to make "sea" to "ea" and another step to make "eat" to "ea".

Python solution

class Solution:
    def minDistance(self, word1: str, word2: str) -> int:
        m, n = len(word1), len(word2)
        f = [[0] * (n + 1) for _ in range(m + 1)]
        for i in range(1, m + 1):
            f[i][0] = i
        for j in range(1, n + 1):
            f[0][j] = j
        for i, a in enumerate(word1, 1):
            for j, b in enumerate(word2, 1):
                if a == b:
                    f[i][j] = f[i - 1][j - 1]
                else:
                    f[i][j] = min(f[i - 1][j], f[i][j - 1]) + 1
        return f[m][n]

Complexity

Pattern: Dynamic Programming

Define a state, write the transition, and stop recomputing the same subproblem. LeetCode 583. Delete Operation for Two Strings is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Dynamic Programming.

The dynamic programming guide has the Python template for the pattern and the 481 LeetCode problems that use it.

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