Interleaving String

Problem page:https://leetcode.com/problems/interleaving-string

Solution

class Solution:
    def isInterleave(self, s1: str, s2: str, s3: str) -> bool:
        m, n, l = len(s1), len(s2), len(s3)
        if m + n != l:
            return False
        dp = [[False] * (n + 1) for _ in range(m + 1)]
        dp[0][0] = True
        for i in range(1, m + 1):
            dp[i][0] = dp[i - 1][0] and s1[i-1] == s3[i-1]
        for i in range(1, n + 1):
            dp[0][i] = dp[0][i - 1] and s2[i-1] == s3[i-1]
        for i in range(1, m + 1):
            for j in range(1, n + 1):
                dp[i][j] = (dp[i-1][j] and s1[i-1] == s3[i+j-1]) or (dp[i][j-1] and s2[j-1]==s3[i+j-1])
        return dp[m][n]

Complexity

• time: O(n * m)
• space: O(n * m)