feat: add swift implementation to lcp problem: No.19 (#3758)

Author: klever34

lcp/LCP 19. 秋叶收藏集/README.md

@@ -200,6 +200,35 @@ function minimumOperations(leaves: string): number {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func minimumOperations(_ leaves: String) -> Int {
+        let n = leaves.count
+        let inf = Int.max / 2
+        var f = Array(repeating: [inf, inf, inf], count: n)
+        let leavesArray = Array(leaves)
+
+        f[0][0] = leavesArray[0] == "r" ? 0 : 1
+
+        for i in 1..<n {
+            if leavesArray[i] == "r" {
+                f[i][0] = f[i - 1][0]
+                f[i][1] = min(f[i - 1][0], f[i - 1][1]) + 1
+                f[i][2] = min(f[i - 1][1], f[i - 1][2])
+            } else {
+                f[i][0] = f[i - 1][0] + 1
+                f[i][1] = min(f[i - 1][0], f[i - 1][1])
+                f[i][2] = min(f[i - 1][1], f[i - 1][2]) + 1
+            }
+        }
+
+        return f[n - 1][2]
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcp/LCP 19. 秋叶收藏集/Solution.swift

@@ -0,0 +1,24 @@
+class Solution {
+    func minimumOperations(_ leaves: String) -> Int {
+        let n = leaves.count
+        let inf = Int.max / 2
+        var f = Array(repeating: [inf, inf, inf], count: n)
+        let leavesArray = Array(leaves)
+        
+        f[0][0] = leavesArray[0] == "r" ? 0 : 1
+        
+        for i in 1..<n {
+            if leavesArray[i] == "r" {
+                f[i][0] = f[i - 1][0]
+                f[i][1] = min(f[i - 1][0], f[i - 1][1]) + 1
+                f[i][2] = min(f[i - 1][1], f[i - 1][2])
+            } else {
+                f[i][0] = f[i - 1][0] + 1
+                f[i][1] = min(f[i - 1][0], f[i - 1][1])
+                f[i][2] = min(f[i - 1][1], f[i - 1][2]) + 1
+            }
+        }
+        
+        return f[n - 1][2]
+    }
+}