copyListWithRandomPointer

Author: zeroliu

src/copyListWithRandomPointer/copyListWithRandomPointer.java

@@ -0,0 +1,40 @@
+/**
+ * Definition for singly-linked list with a random pointer.
+ * class RandomListNode {
+ *     int label;
+ *     RandomListNode next, random;
+ *     RandomListNode(int x) { this.label = x; }
+ * };
+ */
+public class Solution {
+    public RandomListNode copyRandomList(RandomListNode head) {
+        if (head == null) { return null; }
+        
+        HashMap<RandomListNode, RandomListNode> map = new HashMap<RandomListNode, RandomListNode>();
+        LinkedList<RandomListNode> queue = new LinkedList<RandomListNode>();
+        queue.add(head);
+        RandomListNode newHead = new RandomListNode(head.label);
+        map.put(head, newHead);
+        while (queue.size() > 0) {
+            RandomListNode node = queue.poll();
+            RandomListNode newNode = map.get(node);
+                
+            if (node.next != null) {
+                if (!map.containsKey(node.next)) {
+                    RandomListNode nextNode = new RandomListNode(node.next.label);
+                    map.put(node.next, nextNode);
+                }
+                queue.add(node.next);
+                newNode.next = map.get(node.next);
+            }
+            if (node.random != null) {
+                if (!map.containsKey(node.random)) {
+                    RandomListNode randNode = new RandomListNode(node.random.label);
+                    map.put(node.random, randNode);
+                }
+                newNode.random = map.get(node.random);
+            }
+        }
+        return newHead;
+    }
+}