【leetcode刷题】20T36-编辑距离

示例 1:
输入: word1 = "horse", word2 = "ros"
输出: 3
解释: 
horse -> rorse (将 'h' 替换为 'r')
rorse -> rose (删除 'r')
rose -> ros (删除 'e')

示例 2:
输入: word1 = "intention", word2 = "execution"
输出: 5
解释: 
intention -> inention (删除 't')
inention -> enention (将 'i' 替换为 'e')
enention -> exention (将 'n' 替换为 'x')
exention -> exection (将 'n' 替换为 'c')
exection -> execution (插入 'u')

class Solution(object):
    def minDistance(self, word1, word2):
        """
        :type word1: str
        :type word2: str
        :rtype: int
        """
        dis = [[0] * (len(word2) + 1) for i in range(len(word1) + 1)]
        dis[0] = [i for i in range(len(word2) + 1)]
        for i in range(1, len(word1) + 1):
            dis[i][0] = i
            for j in range(1, len(word2) + 1):
                # word1[i - 1] == word2[j - 1]，w[0,...,i]与w2[0,...,j]编辑距离等于w[0,...,i-1]与w2[0,...,j-1]的
                if word1[i - 1] == word2[j - 1]:
                    dis[i][j] = dis[i - 1][j - 1]
                # 否则，等于相邻三个值的最小值+1
                else:
                    dis[i][j] = min(dis[i - 1][j], dis[i][j - 1], dis[i - 1][j - 1]) + 1
        return dis[-1][-1]