algorithms/leetcode/dynamic-programming/minDistance.go at master · TTWShell/algorithms · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
/* https://leetcode.com/problems/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:

	Insert a character
	Delete a character
	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')
*/

package ldp

func minDistance(word1 string, word2 string) int {
	min := func(a, b int) int {
		if a < b {
			return a
		}
		return b
	}

	m, n := len(word1), len(word2)
	dp := make([][]int, m+1, m+1)
	for i := range dp {
		dp[i] = make([]int, n+1, n+1)
	}

	for i := 0; i <= m; i++ {
		dp[i][0] = i
	}
	for j := 0; j <= n; j++ {
		dp[0][j] = j
	}

	for i := 1; i <= m; i++ {
		for j := 1; j <= n; j++ {
			if word1[i-1] == word2[j-1] {
				dp[i][j] = dp[i-1][j-1]
			} else {
				dp[i][j] = min(min(dp[i-1][j], dp[i][j-1]), dp[i-1][j-1]) + 1
			}
		}
	}
	return dp[m][n]
}