LeetCode : 72. Edit Distance 编辑距离-蒲公英云

LeetCode : 72. Edit Distance 编辑距离

试题
Given two words word1 and word2, find the minimum number of operations required to convert word1 to word2.

You have the following 3 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’)
代码
类似思路

class Solution {
    public int minDistance(String word1, String word2) {
        int len1 = word1.length(), len2 = word2.length();
        int[][] dp = new int[len1+1][len2+1];
        //  初始化：在0,0位置为0,在0,i或者i,0位置为i
        for(int i=1; i<=len1; i++){
            dp[i][0] = i;
        }
        for(int i=1; i<=len2; i++){
            dp[0][i] = i;
        } 
        for(int i=1; i<=len1; i++){
            for(int j=1; j<=len2; j++){
                if(word1.charAt(i-1)==word2.charAt(j-1)){
                    dp[i][j] = dp[i-1][j-1];
                }else{
                    //  存在三种操作：替换（子问题变成i-1，j-1），插入（子问题变成i，j-1），删除（子问题变成i-1，j）
                    dp[i][j] = Math.min(dp[i-1][j-1], Math.min(dp[i-1][j], dp[i][j-1])) + 1;
                }
            }
        }
        return dp[len1][len2];
    }
}