583. Delete Operation for Two String

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Given two words word1 and word2, find the minimum number of steps required to make word1 and word2 the same, where in each step you can delete one character in either string.

Example 1:

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Input: "sea", "eat"
Output: 2
Explanation: You need one step to make "sea" to "ea" and another step to make "eat" to "ea".

Note:
The length of given words won’t exceed 500.
Characters in given words can only be lower-case letters.

解法1：

这题和edit distance的思路一样。用二维dp即可解决。
C++

1

Java

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public class Solution {
    public int minDistance(String word1, String word2) {
        int m = word1.length();
        int n = word2.length();
        int[][] dp = new int[m + 1][n + 1];
        // first row
        for (int i = 0; i <= n; i++) {
            dp[0][i] = i;
        }
        // first col
        for (int i = 0; i <= m; i++) {
            dp[i][0] = i;
        }
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (word1.charAt(i - 1) == word2.charAt(j - 1)) {
                    dp[i][j] = Math.min(dp[i][j - 1] + 1, Math.min(dp[i - 1][j] + 1, dp[i - 1][j - 1]));
                } else {
                    dp[i][j] = Math.min(dp[i][j - 1] + 1, Math.min(dp[i - 1][j] + 1, dp[i - 1][j - 1] + 2));
                }
            }
        }
        return dp[m][n];
    }
}