72. Edit Distance - LeetCode Solution

class Solution:
    def minDistance(self, word1: str, word2: str) -> int:
        if not word1 and not word2:
            return 0
        if word1 == word2:
            return 0
        dp = []
       
        for i in range(len(word1)+1):
            a = []
            for j in range(len(word2)+1):
                a.append(0)
            dp.append(a)
            
        for i in range(len(word1)+1):
            dp[i][0] = i
        
        for i in range(len(word2) +1):
            dp[0][i] = i
            
        
        for i in range(1, len(word1)+1, 1):
            for j in range(1, len(word2)+1, 1):
                if word1[i-1] == word2[j-1]:
                    dp[i][j] = dp[i-1][j-1]
                else:
                    dp[i][j] = min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1]) + 1
        return dp[-1][-1]