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Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values. Example 1: Example 2: 阅读全文
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Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of th 阅读全文
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Given a complete binary tree, count the number of nodes. 题目含义：给定一个完整二叉树，求所有节点数 百度百科中完全二叉树的定义如下：若设二叉树的深度为h，除第 h 层外，其它各层 (1～h-1) 的结点数都达到最大个数，第 h 层所有的结点都 阅读全文
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Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in the array whic 阅读全文
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Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number m 阅读全文
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Given a singly linked list, return a random node's value from the linked list. Each node must have the same probability of being chosen. Follow up:Wha 阅读全文
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There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every 阅读全文
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You are playing the following Nim Game with your friend: There is a heap of stones on the table, each time one of you take turns to remove 1 to 3 ston 阅读全文
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Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive. The update(i, val) function modifies nums by upd 阅读全文
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Given an unsorted array nums, reorder it such that nums[0] < nums[1] > nums[2] < nums[3].... Example:(1) Given nums = [1, 5, 1, 1, 6, 4], one possible 阅读全文
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You are given an integer array nums and you have to return a new counts array. The counts array has the property where counts[i] is the number of smal 阅读全文
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Given a string of numbers and operators, return all possible results from computing all the different possible ways to group numbers and operators. Th 阅读全文
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Given a list of non negative integers, arrange them such that they form the largest number. For example, given [3, 30, 34, 5, 9], the largest formed n 阅读全文
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You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k. Define a pair (u,v) which consists of one element from th 阅读全文
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Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element. For exam 阅读全文
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You are given an integer array sorted in ascending order (may contain duplicates), you need to split them into several subsequences, where each subseq 阅读全文
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You are given two non-empty linked lists representing two non-negative integers. The most significant digit comes first and each of their nodes contai 阅读全文
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Given a singly linked list, group all odd nodes together followed by the even nodes. Please note here we are talking about the node number and not the 阅读全文
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Sort a linked list in O(n log n) time using constant space complexity. 含义：为一个列表排序，要求空间复杂度为常量 思路：使用归并排序 1 public class Solution { 2 public ListNode sor 阅读全文
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Sort a linked list using insertion sort. 含义：用插入排序来对列表进行排序 思路：可以构建一个临时的链表，然后将待排序的链表的每一个节点插入到临时链表中 // 插入排序 public ListNode insertionSortList(ListNode he 阅读全文