leetcode------Edit Distance

5740 단어 LeetCode
제목:
Edit Distance
통과율:
26.1%
난이도:
어렵다
 
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 characterb) Delete a characterc) Replace a character
이 문제는 동적 기획의 고전적인 문제로 공식은 다음과 같다.
1、s1.length==0,return s2.length;
2、s2.length==0,return s1.length;
3、if  s1.charat(i)==s2.charat(j),res[i][j]=res[i-1][j-1]
  else  res[i][j]=min(res[i-1][j],res[i][j-1],res[i-1][i-1]+1)
코드:
 1 public class Solution {

 2     public int minDistance(String word1, String word2) {

 3 int len1 = word1.length();

 4     int len2 = word2.length();

 5  

 6     // len1+1, len2+1, because finally return dp[len1][len2]

 7     int[][] dp = new int[len1 + 1][len2 + 1];

 8  

 9     for (int i = 0; i <= len1; i++) 

10         dp[i][0] = i;

11     

12     for (int j = 0; j <= len2; j++) 

13         dp[0][j] = j;

14     

15  

16     //iterate though, and check last char

17     for (int i = 1; i <= len1; i++) {

18         char c1 = word1.charAt(i-1);

19         for (int j = 1; j <= len2; j++) {

20             char c2 = word2.charAt(j-1);

21  

22             //if last two chars equal

23             if (c1 == c2) {

24                 //update dp value for +1 length

25                 dp[i][j] = dp[i-1][j-1];

26             } else {

27                 int replace = dp[i-1][j-1] + 1;

28                 int insert = dp[i-1][j] + 1;

29                 int delete = dp[i][j-1] + 1;

30  

31                 int min = Math.min(replace, insert);

32                 min = Math.min(min,delete);

33                 dp[i][j] = min;

34             }

35         }

36     }

37  

38     return dp[len1][len2];

39     }

40 }

 
 

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