leetcode--Edit Distance-蒲公英云

leetcode--Edit Distance

短命女 2021-10-25 12:40 411阅读 0赞

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

public class Solution {
   /**
     * dynamic programming. Very basic problem.
     * @param word1 -String 
     * @param word2 -String
     * @return  int -number of modifications to change word1 to word2
     * @author Averill Zheng
     * @version 2014-06-24
     * @since JDK 1.7
     */
    public int minDistance(String word1, String word2) {
        int column = word1.length(), row = word2.length();
        if(row == 0)
            return column;
        if(column == 0)
            return row;
        int[][] changes = new int[row + 1][column + 1];
        for(int i = 0; i < column + 1; ++i)
            changes[0][i] = i;
        for(int i = 0; i < row + 1; ++i)
            changes[i][0] = i;
        for(int i = 1; i < row + 1; ++i){
            for(int j = 1; j < column + 1; ++j){
                if(word1.charAt(j - 1) == word2.charAt(i - 1))
                    changes[i][j] = Math.min(changes[i - 1][j - 1], 1 + Math.min(changes[i - 1][j], 
                            changes[i][j - 1]));
                else
                    changes[i][j] = Math.min(1 + changes[i - 1][j - 1], 1 + Math.min(changes[i - 1][j], 
                            changes[i][j - 1]));
            }
        }
        return changes[row][column]; 
    }
}