feat: add swift implementation to lcci problem: No.04.01

lcci/04.01.Route Between Nodes/README.md

@@ -180,6 +180,40 @@ function findWhetherExistsPath(
 }
 ```
 
+```swift
+class Solution {
+    private var g: [[Int]]!
+    private var vis: [Bool]!
+    private var target: Int!
+
+    func findWhetherExistsPath(_ n: Int, _ graph: [[Int]], _ start: Int, _ target: Int) -> Bool {
+        vis = [Bool](repeating: false, count: n)
+        g = [[Int]](repeating: [], count: n)
+        self.target = target
+        for e in graph {
+            g[e[0]].append(e[1])
+        }
+        return dfs(start)
+    }
+
+    private func dfs(_ i: Int) -> Bool {
+        if i == target {
+            return true
+        }
+        if vis[i] {
+            return false
+        }
+        vis[i] = true
+        for j in g[i] {
+            if dfs(j) {
+                return true
+            }
+        }
+        return false
+    }
+}
+```
+
 <!-- tabs:end -->
 
 ### 方法二：BFS

lcci/04.01.Route Between Nodes/README_EN.md

@@ -187,6 +187,40 @@ function findWhetherExistsPath(
 }
 ```
 
+```swift
+class Solution {
+    private var g: [[Int]]!
+    private var vis: [Bool]!
+    private var target: Int!
+
+    func findWhetherExistsPath(_ n: Int, _ graph: [[Int]], _ start: Int, _ target: Int) -> Bool {
+        vis = [Bool](repeating: false, count: n)
+        g = [[Int]](repeating: [], count: n)
+        self.target = target
+        for e in graph {
+            g[e[0]].append(e[1])
+        }
+        return dfs(start)
+    }
+
+    private func dfs(_ i: Int) -> Bool {
+        if i == target {
+            return true
+        }
+        if vis[i] {
+            return false
+        }
+        vis[i] = true
+        for j in g[i] {
+            if dfs(j) {
+                return true
+            }
+        }
+        return false
+    }
+}
+```
+
 <!-- tabs:end -->
 
 ### Solution 2: BFS

lcci/04.01.Route Between Nodes/Solution.swift

@@ -0,0 +1,31 @@
+class Solution {
+    private var g: [[Int]]!
+    private var vis: [Bool]!
+    private var target: Int!
+
+    func findWhetherExistsPath(_ n: Int, _ graph: [[Int]], _ start: Int, _ target: Int) -> Bool {
+        vis = [Bool](repeating: false, count: n)
+        g = [[Int]](repeating: [], count: n)
+        self.target = target
+        for e in graph {
+            g[e[0]].append(e[1])
+        }
+        return dfs(start)
+    }
+
+    private func dfs(_ i: Int) -> Bool {
+        if i == target {
+            return true
+        }
+        if vis[i] {
+            return false
+        }
+        vis[i] = true
+        for j in g[i] {
+            if dfs(j) {
+                return true
+            }
+        }
+        return false
+    }
+}