LeetCode-in-All
72. Edit Distance
Hard
Given two strings word1 and word2, return the minimum number of operations required to convert word1 to word2.
You have the following three 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’)
Constraints:
0 <= word1.length, word2.length <= 500word1andword2consist of lowercase English letters.
Solution
class Solution {
fun minDistance(word1: String, word2: String): Int {
val n1 = word1.length
val n2 = word2.length
if (n2 > n1) {
return minDistance(word2, word1)
}
val dp = IntArray(n2 + 1)
for (j in 0..n2) {
dp[j] = j
}
for (i in 1..n1) {
var pre = dp[0]
dp[0] = i
for (j in 1..n2) {
val tmp = dp[j]
dp[j] = if (word1[i - 1] != word2[j - 1]) 1 + Math.min(pre, Math.min(dp[j], dp[j - 1])) else pre
pre = tmp
}
}
return dp[n2]
}
}