feat: add swift implementation to lcp problem: No.41 (#3783)

Author: klever34

lcp/LCP 41. 黑白翻转棋/README.md

@@ -292,6 +292,70 @@ func abs(x int) int {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    private var m = 0
+    private var n = 0
+    private var chessboard: [String] = []
+    
+    func flipChess(_ chessboard: [String]) -> Int {
+        self.m = chessboard.count
+        self.n = chessboard[0].count
+        self.chessboard = chessboard
+        var ans = 0
+        
+        for i in 0..<m {
+            for j in 0..<n {
+                if Array(chessboard[i])[j] == "." {
+                    ans = max(ans, bfs(i, j))
+                }
+            }
+        }
+        return ans
+    }
+    
+    private func bfs(_ i: Int, _ j: Int) -> Int {
+        var queue: [[Int]] = [[i, j]]
+        var g = chessboard.map { Array($0) }
+        g[i][j] = "X"
+        var count = 0
+        
+        while !queue.isEmpty {
+            let p = queue.removeFirst()
+            let i = p[0], j = p[1]
+            
+            for a in -1...1 {
+                for b in -1...1 {
+                    if a == 0 && b == 0 { continue }
+                    
+                    var x = i + a, y = j + b
+                    while x >= 0 && x < m && y >= 0 && y < n && g[x][y] == "O" {
+                        x += a
+                        y += b
+                    }
+                    
+                    if x >= 0 && x < m && y >= 0 && y < n && g[x][y] == "X" {
+                        x -= a
+                        y -= b
+                        count += max(abs(x - i), abs(y - j))
+                        
+                        while x != i || y != j {
+                            g[x][y] = "X"
+                            queue.append([x, y])
+                            x -= a
+                            y -= b
+                        }
+                    }
+                }
+            }
+        }
+        return count
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcp/LCP 41. 黑白翻转棋/Solution.swift

@@ -0,0 +1,59 @@
+class Solution {
+    private var m = 0
+    private var n = 0
+    private var chessboard: [String] = []
+    
+    func flipChess(_ chessboard: [String]) -> Int {
+        self.m = chessboard.count
+        self.n = chessboard[0].count
+        self.chessboard = chessboard
+        var ans = 0
+        
+        for i in 0..<m {
+            for j in 0..<n {
+                if Array(chessboard[i])[j] == "." {
+                    ans = max(ans, bfs(i, j))
+                }
+            }
+        }
+        return ans
+    }
+    
+    private func bfs(_ i: Int, _ j: Int) -> Int {
+        var queue: [[Int]] = [[i, j]]
+        var g = chessboard.map { Array($0) }
+        g[i][j] = "X"
+        var count = 0
+        
+        while !queue.isEmpty {
+            let p = queue.removeFirst()
+            let i = p[0], j = p[1]
+            
+            for a in -1...1 {
+                for b in -1...1 {
+                    if a == 0 && b == 0 { continue }
+                    
+                    var x = i + a, y = j + b
+                    while x >= 0 && x < m && y >= 0 && y < n && g[x][y] == "O" {
+                        x += a
+                        y += b
+                    }
+                    
+                    if x >= 0 && x < m && y >= 0 && y < n && g[x][y] == "X" {
+                        x -= a
+                        y -= b
+                        count += max(abs(x - i), abs(y - j))
+                        
+                        while x != i || y != j {
+                            g[x][y] = "X"
+                            queue.append([x, y])
+                            x -= a
+                            y -= b
+                        }
+                    }
+                }
+            }
+        }
+        return count
+    }
+}