Given a linked list, determine if it has a cycle in it. Follow up: Can you solve it without using extra space? 思考：快慢指針，快指針一次走兩步，慢指針一次一步。若快指針跟慢指針指向同一個結點，則有環。若快指針到達鏈表末尾即指向NULL

Given a list, rotate the list to the right by?k?places, where?k?is non-negative. For example:Given?1->2->3->4->5->NULL?and?k?=?2,return?4->5->1->2->3->NULL. 思考：先首尾連成環，head前進(len-k%len)步，拆環

Sort a linked list using insertion sort. 鏈表的插入排序，其實有2種特殊情況： 1、插入的值插入到已排序的末尾。 leetcode并查集，2、插入的值插入到已排序的最前端。 主要設置了3個指針。 1、pStart是已排序鏈表的開始位置。 2、pInsert是待插入的位置。 LE

題目： Given preorder and inorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. 解題思路： 前序遍歷序列的第一個元素肯定為根節點；然后再在中序遍歷序列中找到該節點，并以

? Given preorder and inorder traversal of a tree, construct the binary tree. Note:You may assume that duplicates do not exist in the tree. ? leetcode 最長公共子序列？這道題要求用先序和中序遍歷來建立二叉樹，跟之前那道Construct Binary Tree from Inorde

鏈表的歸并排序 超時的代碼 class Solution:def merge(self, head1, head2):if head1 == None:return head2if head2 == None:return head1# head1 and head2 point to the same link listif head1 == head2:return head1head = Nonetail =

Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2 ↘ c1 → c2 → c3 ↗ B: b1 → b2 → b3 begin to intersect at node c1. /*** Definition for singly-linked

Intersection of Two Linked Lists: Write a program to find the node at which the intersection of two singly linked lists begins. For example, the following two linked lists: A: a1 → a2↘c1 → c2 → c3↗ B: b1 → b2 → b3 leetcode121，begin to intersect at

Palindrome Linked List Given a singly linked list, determine if it is a palindrome. Follow up:Could you do it in O(n) time and O(1) space? https://leetcode.com/problems/palindrome-linked-list/ ? LeetCode。? ? ? 判斷單鏈表是否為回文，要求時間復雜度O

Given a singly linked list?L:?L0→L1→…→Ln-1→Ln,reorder it to:?L0→Ln→L1→Ln-1→L2→Ln-2→… You must do this in-place without altering the nodes' values. For example,Given?{1,2,3,4}, reorder it to?{1,4,2,3}. ? LeetCode、OH! MY GOD! I HATE LINKED