1def edit_distance(word1, word2):
2 m, n = len(word1), len(word2)
3 dp = [[0] * (n + 1) for _ in range(m + 1)]
4 for r in range(m + 1):
5 dp[r][0] = r
6 for c in range(n + 1):
7 dp[0][c] = c
8 for r in range(1, m + 1):
9 for c in range(1, n + 1):
10 if word1[r - 1] == word2[c - 1]:
11 dp[r][c] = dp[r - 1][c - 1]
12 else:
13 dp[r][c] = 1 + min(dp[r - 1][c], dp[r][c - 1], dp[r - 1][c - 1])
14 return dp[m][n]