Create Copy List with Random Pointer.py

Author: sugia

Copy List with Random Pointer.py

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+'''
+A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.
+
+Return a deep copy of the list.
+
+
+'''
+
+# Definition for singly-linked list with a random pointer.
+# class RandomListNode(object):
+#     def __init__(self, x):
+#         self.label = x
+#         self.next = None
+#         self.random = None
+
+class Solution(object):
+    def copyRandomList(self, head):
+        """
+        :type head: RandomListNode
+        :rtype: RandomListNode
+        """
+        if not head:
+            return None
+        
+        dic = {}
+        cur = head
+        while cur:
+            if cur not in dic:
+                mirror = RandomListNode(cur.label)
+                dic[cur] = mirror
+            
+            if cur.next:
+                if cur.next not in dic:
+                    mirror = RandomListNode(cur.next.label)
+                    dic[cur.next] = mirror
+                    
+                dic[cur].next = dic[cur.next]
+                
+            if cur.random:
+                if cur.random not in dic:
+                    mirror = RandomListNode(cur.random.label)
+                    dic[cur.random] = mirror
+                    
+                dic[cur].random = dic[cur.random]
+                
+            cur = cur.next
+            
+        return dic[head]