Merge pull request #1056 from Mahim1997/dev/133_swift

133. Clone Graph

Author: Ahmad-A0

Diff for: swift/133-Clone-Graph.swift

@@ -0,0 +1,33 @@
+/**
+ * Definition for a Node.
+ * public class Node {
+ *     public var val: Int
+ *     public var neighbors: [Node?]
+ *     public init(_ val: Int) {
+ *         self.val = val
+ *         self.neighbors = []
+ *     }
+ * }
+ */
+
+class Solution {
+    var mapping: [Node?: Node?] = [:]
+    
+    func cloneGraph(_ node: Node?) -> Node? {
+        guard let node = node else { return nil }
+        // check if cache exists
+        
+        if mapping[node] != nil {
+            return mapping[node]!
+        }
+        
+        // otherwise, create a node, cache it, recurse for children
+        let newNode = Node(node.val)
+        mapping[node] = newNode
+        
+        node.neighbors.forEach { neighbor in
+            newNode.neighbors.append(cloneGraph(neighbor))
+        }
+        return newNode
+    }
+}