feat: add swift implementation to lcof problem: No.13 (doocs#2865)

Author: klever34

lcof/面试题13. 机器人的运动范围/README.md

@@ -202,6 +202,43 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    private var vis: [[Bool]] = []
+    private var m: Int = 0
+    private var n: Int = 0
+    private var k: Int = 0
+
+    func movingCount(_ m: Int, _ n: Int, _ k: Int) -> Int {
+        self.m = m
+        self.n = n
+        self.k = k
+        self.vis = Array(repeating: Array(repeating: false, count: n), count: m)
+        return dfs(0, 0)
+    }
+
+    private func dfs(_ i: Int, _ j: Int) -> Int {
+        if i >= m || j >= n || vis[i][j] || (digitSum(i) + digitSum(j)) > k {
+            return 0
+        }
+        vis[i][j] = true
+        return 1 + dfs(i + 1, j) + dfs(i, j + 1)
+    }
+
+    private func digitSum(_ num: Int) -> Int {
+        var num = num
+        var sum = 0
+        while num > 0 {
+            sum += num % 10
+            num /= 10
+        }
+        return sum
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题13. 机器人的运动范围/Solution.swift

@@ -0,0 +1,32 @@
+class Solution {
+    private var vis: [[Bool]] = []
+    private var m: Int = 0
+    private var n: Int = 0
+    private var k: Int = 0
+
+    func movingCount(_ m: Int, _ n: Int, _ k: Int) -> Int {
+        self.m = m
+        self.n = n
+        self.k = k
+        self.vis = Array(repeating: Array(repeating: false, count: n), count: m)
+        return dfs(0, 0)
+    }
+
+    private func dfs(_ i: Int, _ j: Int) -> Int {
+        if i >= m || j >= n || vis[i][j] || (digitSum(i) + digitSum(j)) > k {
+            return 0
+        }
+        vis[i][j] = true
+        return 1 + dfs(i + 1, j) + dfs(i, j + 1)
+    }
+
+    private func digitSum(_ num: Int) -> Int {
+        var num = num
+        var sum = 0
+        while num > 0 {
+            sum += num % 10
+            num /= 10
+        }
+        return sum
+    }
+}