算法题LC76：edit-distance

动态规划：
题目描述：
给定两个单词word1和word2，请计算将word1转换为word2至少需要多少步操作。
你可以对一个单词执行以下3种操作：
a）在单词中插入一个字符
b）删除单词中的一个字符
c）替换单词中的一个字符

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)
You have the following 3 operations permitted on a word:

a) Insert a character
b) Delete a character
c) Replace a character
输入描述：

输出描述：

示例1：
输入：

输出：
        
代码：

public class Solution {
    public int minDistance(String word1, String word2) {
        int[][] dp = new int[word1.length() + 1][word2.length() + 1];
        for (int i = 0; i < dp[0].length; i ++ ) dp[0][i] = i;
        for (int i = 0; i < dp.length; i ++ ) dp[i][0] = i;
        for (int i = 1; i < dp.length; i ++ ) {
            for (int j = 1; j < dp[0].length; j ++ ) {
                if(word1.charAt(i - 1) == word2.charAt(j - 1)) dp[i][j] = dp[i - 1][j - 1];
                else dp[i][j] = Math.min(Math.min(dp[i - 1][j] + 1, dp[i][j - 1] + 1), dp[i - 1][j - 1] + 1);
            }
        }
        return dp[word1.length()][word2.length()];
    }
}