feat(leetcode): add No.138

Author: mickey0524

138.Copy-List-with-Random-Pointer.py

@@ -0,0 +1,28 @@
+# https://leetcode.com/problems/copy-list-with-random-pointer/description/
+#
+# algorithms
+# Medium (25.56%)
+# Total Accepted:    195.5K
+# Total Submissions: 765K
+# beats 100.0% of python submissions
+
+# 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):
+        dic = {}
+        m = n = head
+        while m:  # copy node itself
+            dic[m] = RandomListNode(m.label)
+            m = m.next
+        while n:  # link the node and copy the random pointer of the current node
+            dic[n].next = dic.get(n.next)
+            dic[n].random = dic.get(n.random)
+            n = n.next
+        return dic.get(head)