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MAY-31 2020 Challenge

Edit Distance


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:

1. Insert a character
2. Delete a character
3. 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')
Example 2:
Input: word1 = "intention", word2 = "execution"
Output: 5
Explanation: 
intention -> inention (remove 't')
inention -> enention (replace 'i' with 'e')
enention -> exention (replace 'n' with 'x')
exention -> exection (replace 'n' with 'c')
exection -> execution (insert 'u')


Solution in Java :


class Solution {
    public int minDistance(String word1, String word2) {
        int m = word1.length(), n = word2.length();

        int[][] dp = new int[m + 1][n + 1];

        for(int i = 0; i <= m; i++) {
            dp[i][0] = i;
        }
        for(int j = 0; j <= n; j++) {
            dp[0][j] = j;
        }

        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] = dp[i - 1][j - 1];
                else
                    dp[i][j] = min(dp[i - 1][j - 1] + 1, dp[i - 1][j] + 1, dp[i][j - 1] + 1);
            }
        }
        return dp[m][n];
    }

    private int min(int a, int b, int c) {
        if(a <= b && a <= c) return a;
        else if (b <= a && b <= c) return b;
        else return c;
    }
}
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