1. 题目

leetcode.cn/problems/in…

2. 解析

使用动态规划 确定方程式 dp[i][j] = (dp[i][j - 1] and s2[j - 1] == s3[i + j - 1]) or ( dp[i - 1][j] and s1[i - 1] == s3[i + j - 1])

3. 核心代码

class Solution(object):
    def fun(self, s1, s2, s3):
        l1, l2, l3 = len(s1), len(s2), len(s3)
        if l1 + l2 != l3:
            return False
        dp = [[False] * (l2 + 1) for _ in range(l1 + 1)]
        for i in range(l1 + 1):
            for j in range(l2 + 1):
                if i == j == 0:
                    dp[0][0] = True
                elif j == 0:
                    dp[i][0] = dp[i - 1][0] and s1[i - 1] == s3[i - 1]
                elif i == 0:
                    dp[0][j] = dp[0][j - 1] and s2[j - 1] == s3[j - 1]
                else:
                    dp[i][j] = (dp[i][j - 1] and s2[j - 1] == s3[i + j - 1]) or (
                            dp[i - 1][j] and s1[i - 1] == s3[i + j - 1])
        return dp[-1][-1]


if __name__ == '__main__':
    s = Solution()
    print(s.fun("aabcc", "dbbca", "aadbbbaccc"))