双指针

CodingProgrammer · web-flow · commit 286e41c41b1f · 2020-12-09T14:17:50.000+08:00
某一个链表扫描退出循环后，只需cur.next指向未扫描完的那个链表的当前节点即可，无需再用while遍历
diff --git a/newcoder/合并有序链表.py b/newcoder/合并有序链表.py
@@ -0,0 +1,85 @@
+'''
+Descripttion: 双指针+伪指针
+version: 1
+Author: Jason
+Date: 2020-12-08 17:45:52
+LastEditors: Jason
+LastEditTime: 2020-12-09 14:15:46
+'''
+
+import random
+
+
+def GenerateRandomList(number, size):
+    temp = [random.randint(0, number)]
+    random_legth = random.randint(0, size)
+    current_length = 0
+    while current_length < random_legth:
+        temp.append(random.randint(1, number))
+        current_length += 1
+    return temp
+
+
+class ListNode:
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
+
+class Solution:
+    def mergeTwoLists(self, l1, l2):
+        # write code here
+        dummy = ListNode(float("inf"))
+        cur = dummy
+        p1, p2 = l1, l2
+        while p1 and p2:
+            if p1.val < p2.val:
+                cur.next = p1
+                p1 = p1.next
+            else:
+                cur.next = p2
+                p2 = p2.next
+            cur = cur.next
+        # 有一个链表扫描完毕后，只需将目前的cur的next指向未扫描完的当前node即可，不用再while去扫描
+        if p1:
+            cur.next = p1
+        else:
+            cur.next = p2
+        return dummy.next
+
+
+s = Solution()
+for _ in range(100):
+
+    nums1 = GenerateRandomList(20, 20)
+    nums2 = GenerateRandomList(20, 20)
+    nums1.sort()
+    nums2.sort()
+    nums_stand = sorted(nums1 + nums2)
+    nodes1 = [ListNode(num) for num in nums1]
+    nodes2 = [ListNode(num) for num in nums2]
+    nodes_stand = [ListNode(num) for num in nums_stand]
+
+    for i in range(len(nums1) - 1):
+        nodes1[i].next = nodes1[i + 1]
+
+    for i in range(len(nums2) - 1):
+        nodes2[i].next = nodes2[i + 1]
+
+    for i in range(len(nums_stand) - 1):
+        nodes_stand[i].next = nodes_stand[i + 1]
+
+    res = s.mergeTwoLists(nodes1[0], nodes2[0])
+
+    cur = nodes_stand[0]
+    while cur:
+        if cur.val != res.val:
+            print("Wrong")
+            print(nums1, nums2)
+            break
+        cur = cur.next
+        res = res.next
+
+    if cur or res:
+        print("Wrong")
+print("Done")
