题目
Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2.
You have the following three operations permitted on a word:
- Insert a character
- Delete a character
- Replace a character
Example 1:
Input: word1 = "horse", word2 = "ros"
Output: 3
Explanation:
horse -> rorse (replace 'h' with 'r')
rorse -> rose (remove 'r')
rose -> ros (remove 'e')
Example 2:
Input: word1 = "intention", word2 = "execution"
Output: 5
Explanation:
intention -> inention (remove 't')
inention -> enention (replace 'i' with 'e')
enention -> exention (replace 'n' with 'x')
exention -> exection (replace 'n' with 'c')
exection -> execution (insert 'u')
Constraints:
0 <= word1.length, word2.length <= 500word1andword2consist of lowercase English letters.
思路
动态规划，与583. Delete Operation for Two Strings类似。
代码
python版本：
class Solution:
def minDistance(self, word1: str, word2: str) -> int:
dp = [[99999]*(len(word2)+1) for _ in range(len(word1)+1)]
for i in range(len(dp)):
for j in range(len(dp[i])):
if i == 0 or j == 0:
dp[i][j] = i+j
elif 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
# [print(i) for i in dp]
return dp[-1][-1]
