Create: 72-Edit-Distance.swift

swift/72-Edit-Distance.swift

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+class Solution {
+ func minDistance(_ word1: String, _ word2: String) -> Int {
+ // No operations needed if strings match
+ if word1 == word2 {
+ return 0
+ }
+
+ let m = word1.count, n = word2.count
+
+ // if one word has no characters, min operations is length of other word
+ if m == 0 {
+ return n
+ }
+ if n == 0 {
+ return m
+ }
+
+ var prev = 0
+ var curr = Array(repeating: 0, count: n + 1)
+
+ // convert the strings into an array
+ let newWord1 = Array(word1)
+ let newWord2 = Array(word2)
+
+ for j in 1...n {
+ curr[j] = j
+ }
+
+ for i in 1...m {
+ var prev = curr[0]
+ curr[0] = i
+ for j in 1...n {
+ let temp = curr[j]
+ if newWord1[i - 1] == newWord2[j - 1] {
+ curr[j] = prev
+ }
+ else {
+ curr[j] = min(prev, min(curr[j - 1], curr[j])) + 1
+ }
+ prev = temp
+ }
+ }
+ return curr[n]
+ }
+}