MayChallenge (61) | 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')

In book of Le Minh Hoang, the problem is type Dynamid Programing.

Build the matrix word2.length() row and word1.length() colum. While word2[i] == word1[j], the result equal result before sub problem, is dq[i-1][j-1]. Else, we have 3 options for change. 

1. Insert word2[i] to word1. => dp[i][j] = dp[i][j-1].

2. Delete word1[j] => dp[i][j] = dp[i-1][j].

3. Replace word1[j] to word2[i] => dp[i][j] = dp[i-1][j-1].

My code:
Humm, i completed challenge May. Thank you for reading !