摘要：
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).For example, this binary tree is symmetric: 1 / \ 2 2 / \ / \3 4 4 3But the following is not: 1 / \ 2 2 \ \ 3 3Note:Bonus points if you could solve it both recursively and iterati... 阅读全文
摘要：
Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.分析：这道题我们新建新的链表，并且此题运用递归手法还是很好做的。首先我们从合并两个链表的头结点开始。链表1的头结点的值小于链表2的头结点的值，因此链表1的头结点将是合并后链表的头结点，反之，链表2的头结点将是合并后链表的头结点。我们继续合并两个链表中剩余的结点。在两个链表中剩下的结点依然是排序的，因此合并这两个链表的 阅读全文
摘要：
Given an array of integers, every element appearsthreetimes except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?题目思路一：这道题要求时间复杂度是O(n),而且要求你不借用空间来实现。但是这道题我能想到的就是兼用map来实现。遍历数组，找出那个只出现一次的元素。class Solution {p 阅读全文