feat: add swift implementation to lcci problem: No.17.23 (doocs#2818)

Author: klever34

lcci/17.23.Max Black Square/README.md

@@ -225,6 +225,38 @@ function findSquare(matrix: number[][]): number[] {
 }
 ```
 
+```swift
+class Solution {
+    func findSquare(_ matrix: [[Int]]) -> [Int] {
+        let n = matrix.count
+        var down = Array(repeating: Array(repeating: 0, count: n), count: n)
+        var right = Array(repeating: Array(repeating: 0, count: n), count: n)
+
+        for i in stride(from: n - 1, through: 0, by: -1) {
+            for j in stride(from: n - 1, through: 0, by: -1) {
+                if matrix[i][j] == 0 {
+                    down[i][j] = (i + 1 < n) ? down[i + 1][j] + 1 : 1
+                    right[i][j] = (j + 1 < n) ? right[i][j + 1] + 1 : 1
+                }
+            }
+        }
+
+        for k in stride(from: n, through: 1, by: -1) {
+            for i in 0...(n - k) {
+                for j in 0...(n - k) {
+                    if down[i][j] >= k && right[i][j] >= k &&
+                       right[i + k - 1][j] >= k && down[i][j + k - 1] >= k {
+                        return [i, j, k]
+                    }
+                }
+            }
+        }
+
+        return []
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/17.23.Max Black Square/README_EN.md

@@ -211,6 +211,38 @@ function findSquare(matrix: number[][]): number[] {
 }
 ```
 
+```swift
+class Solution {
+    func findSquare(_ matrix: [[Int]]) -> [Int] {
+        let n = matrix.count
+        var down = Array(repeating: Array(repeating: 0, count: n), count: n)
+        var right = Array(repeating: Array(repeating: 0, count: n), count: n)
+
+        for i in stride(from: n - 1, through: 0, by: -1) {
+            for j in stride(from: n - 1, through: 0, by: -1) {
+                if matrix[i][j] == 0 {
+                    down[i][j] = (i + 1 < n) ? down[i + 1][j] + 1 : 1
+                    right[i][j] = (j + 1 < n) ? right[i][j + 1] + 1 : 1
+                }
+            }
+        }
+
+        for k in stride(from: n, through: 1, by: -1) {
+            for i in 0...(n - k) {
+                for j in 0...(n - k) {
+                    if down[i][j] >= k && right[i][j] >= k &&
+                       right[i + k - 1][j] >= k && down[i][j + k - 1] >= k {
+                        return [i, j, k]
+                    }
+                }
+            }
+        }
+
+        return []
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- end -->

lcci/17.23.Max Black Square/Solution.swift

@@ -0,0 +1,29 @@
+class Solution {
+    func findSquare(_ matrix: [[Int]]) -> [Int] {
+        let n = matrix.count
+        var down = Array(repeating: Array(repeating: 0, count: n), count: n)
+        var right = Array(repeating: Array(repeating: 0, count: n), count: n)
+        
+        for i in stride(from: n - 1, through: 0, by: -1) {
+            for j in stride(from: n - 1, through: 0, by: -1) {
+                if matrix[i][j] == 0 {
+                    down[i][j] = (i + 1 < n) ? down[i + 1][j] + 1 : 1
+                    right[i][j] = (j + 1 < n) ? right[i][j + 1] + 1 : 1
+                }
+            }
+        }
+        
+        for k in stride(from: n, through: 1, by: -1) {
+            for i in 0...(n - k) {
+                for j in 0...(n - k) {
+                    if down[i][j] >= k && right[i][j] >= k &&
+                       right[i + k - 1][j] >= k && down[i][j + k - 1] >= k {
+                        return [i, j, k]
+                    }
+                }
+            }
+        }
+        
+        return []
+    }
+}