feat: add swift implementation to lcof2 problem: No.110 (doocs#3688)

Author: klever34

lcof2/剑指 Offer II 110. 所有路径/README.md

@@ -189,6 +189,35 @@ func allPathsSourceTarget(graph [][]int) [][]int {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    private var results = [[Int]]()
+    private var graph = [[Int]]()
+
+    func allPathsSourceTarget(_ graph: [[Int]]) -> [[Int]] {
+        self.graph = graph
+        var path = [0]
+        dfs(0, &path)
+        return results
+    }
+
+    private func dfs(_ node: Int, _ path: inout [Int]) {
+        if node == graph.count - 1 {
+            results.append(Array(path))
+            return
+        }
+        
+        for next in graph[node] {
+            path.append(next)
+            dfs(next, &path)
+            path.removeLast()
+        }
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof2/剑指 Offer II 110. 所有路径/Solution.swift

@@ -0,0 +1,24 @@
+class Solution {
+    private var results = [[Int]]()
+    private var graph = [[Int]]()
+
+    func allPathsSourceTarget(_ graph: [[Int]]) -> [[Int]] {
+        self.graph = graph
+        var path = [0]
+        dfs(0, &path)
+        return results
+    }
+
+    private func dfs(_ node: Int, _ path: inout [Int]) {
+        if node == graph.count - 1 {
+            results.append(Array(path))
+            return
+        }
+        
+        for next in graph[node] {
+            path.append(next)
+            dfs(next, &path)
+            path.removeLast()
+        }
+    }
+}