merge two nodelists

Author: springuper

Diff for: mergeTwoLists.py

@@ -0,0 +1,53 @@
+# Definition for singly-linked list.
+class ListNode:
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
+# @param two ListNodes
+# @return a ListNode
+def mergeTwoLists(l1, l2):
+    def getNext(l1, l2):
+        if l1 and l2:
+            return l1.val < l2.val
+        return True if l1 else False
+
+    if not l1 and not l2:
+        return None
+
+    ret = getNext(l1, l2)
+    if ret:
+        l = head = l1
+        l1 = l1.next
+    else:
+        l = head = l2
+        l2 = l2.next
+
+    while l1 or l2:
+        ret = getNext(l1, l2)
+        if ret:
+            l.next = l1
+            l1 = l1.next
+        else:
+            l.next = l2
+            l2 = l2.next
+        l = l.next
+
+    return head
+
+a = ListNode(1)
+b = ListNode(2)
+c = ListNode(4)
+a.next = b
+b.next = c
+
+d = ListNode(3)
+e = ListNode(5)
+d.next = e
+
+l = mergeTwoLists(a, d)
+assert l.val == 1
+assert l.next.val == 2
+assert l.next.next.val == 3
+assert l.next.next.next.val == 4
+assert l.next.next.next.next.val == 5