feat: add swift implementation to lcp problem: No.25 (doocs#3774)

lcp/LCP 25. 古董键盘/README.md

@@ -193,6 +193,41 @@ function keyboard(k: number, n: number): number {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func keyboard(_ k: Int, _ n: Int) -> Int {
+        let mod = 1_000_000_007
+        var c = Array(repeating: Array(repeating: 0, count: k + 1), count: n + 1)
+        for i in 0...n {
+            c[i][0] = 1
+        }
+
+        for i in 1...n {
+            for j in 1...k {
+                c[i][j] = (c[i - 1][j - 1] + c[i - 1][j]) % mod
+            }
+        }
+
+        var f = Array(repeating: Array(repeating: 0, count: 27), count: n + 1)
+        for j in 0..<27 {
+            f[0][j] = 1
+        }
+
+        for i in 1...n {
+            for j in 1..<27 {
+                for h in 0...min(i, k) {
+                    f[i][j] = (f[i][j] + (f[i - h][j - 1] * c[i][h]) % mod) % mod
+                }
+            }
+        }
+
+        return f[n][26]
+    }
+}
+```
+
 <!--- tabs:end -->
 
 <!-- solution:end -->

lcp/LCP 25. 古董键盘/Solution.swift

@@ -0,0 +1,30 @@
+class Solution {
+    func keyboard(_ k: Int, _ n: Int) -> Int {
+        let mod = 1_000_000_007
+        var c = Array(repeating: Array(repeating: 0, count: k + 1), count: n + 1)
+        for i in 0...n {
+            c[i][0] = 1
+        }
+
+        for i in 1...n {
+            for j in 1...k {
+                c[i][j] = (c[i - 1][j - 1] + c[i - 1][j]) % mod
+            }
+        }
+
+        var f = Array(repeating: Array(repeating: 0, count: 27), count: n + 1)
+        for j in 0..<27 {
+            f[0][j] = 1
+        }
+
+        for i in 1...n {
+            for j in 1..<27 {
+                for h in 0...min(i, k) {
+                    f[i][j] = (f[i][j] + (f[i - h][j - 1] * c[i][h]) % mod) % mod
+                }
+            }
+        }
+
+        return f[n][26]
+    }
+}