Leetcode reorder list

linked-list.md

@@ -0,0 +1,34 @@
+# Linked list
+
++ [Reorder List (deque)](#reorder-list-deque)
+
+## Reorder List (deque)
+
+https://leetcode.com/problems/reorder-list/
+
+```python
+# Definition for singly-linked list.
+# class ListNode(object):
+#     def __init__(self, val=0, next=None):
+#         self.val = val
+#         self.next = next
+class Solution(object):
+    def reorderList(self, head):
+        prev, curr = ListNode(0), head
+        q = collections.deque()
+        while head:
+            q.append(head)
+            head = head.next
+
+        i = 1
+        while q:
+            if i & 1:
+                curr = q.popleft()
+            else:
+                curr = q.pop()
+            prev.next = curr
+            prev = curr
+            i += 1
+        if curr: curr.next = None
+
+```