hnxijie的博客

Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2). You are given a target value to search. If found in the array retur

题目来源：https://leetcode.com/problems/find-peak-element/ 点击打开链接 A peak element is an element that is greater than its neighbors. Given an input array where num[i] ≠ num[i+1], find a peak element

题目来源：https://leetcode.com/problems/maximum-depth-of-binary-tree/  本题地址 Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root

题目来源：https://leetcode.com/problems/delete-node-in-a-linked-list/ Write a function to delete a node (except the tail) in a singly linked list, given only access to that node. Supposed the linke

Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the target, whe

题目来源：https://leetcode.com/problems/valid-palindrome/      原题地址 Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example, "A m

题目来源：https://leetcode.com/problems/nim-game/   题目地址 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

题目来源：https://leetcode.com/problems/move-zeroes/ Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements. For exam

题目来源：https://leetcode.com/problems/merge-sorted-array/ Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note: You may assume that nums1 has enough

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit. For example: Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has on

Invert a binary tree. 4 / \ 2 7 / \ / \ 1 3 6 9 to 4 / \ 7 2 / \ / \ 9 6 3 1 递归的方法： /**  * Definition for a binary tree node.  * struct TreeNode {

题目来源：https://leetcode.com/problems/find-minimum-in-rotated-sorted-array-ii/    点击打开链接 Follow up for "Find Minimum in Rotated Sorted Array": What if duplicates are allowed? Would this affect

题目来源：https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/    点击打开链接 Suppose a sorted array is rotated at some pivot unknown to you beforehand. (i.e., 0 1 2 4 5 6 7 might become 

题目来源：https://leetcode.com/problems/4sum/点击打开链接 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

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit. For example: Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has on

Determine whether an integer is a palindrome. Do this without extra space. Some hints: Could negative integers be palindromes? (ie, -1) If you are thinking of converting the integer to string, no

Given a binary tree, find its maximum depth. The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node. 分析： 递归 /** * Definition for

Given numRows, generate the first numRows of Pascal's triangle. For example, given numRows = 5, Return [ [1], [1,1], [1,2,1], [1,3,3,1], [1,4,6,4,1] ] 分析  要得到一个帕斯卡三角， 我们只需要找到规律即可。

Given an array and a value, remove all instances of that > value in place and return the new length. The order of elements can be changed. It doesn't matter what you leave beyond the new length.

Given a non-negative number represented as an array of digits, plus one to the number. The digits are stored such that the most significant digit is at the head of the list. class Solution66{

Given two sorted integer arrays nums1 and nums2, merge nums2 into nums1 as one sorted array. Note: You may assume that nums1 has enough space (size that is greater or equal to m + n) to hold addit

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Note: Elements in a triplet (a,b,c

题目来源：https://leetcode.com/problems/search-a-2d-matrix/   点击打开链接 Write an efficient algorithm that searches for a value in an m x n matrix. This matrix has the following properties: Intege

题目来源：点击打开链接https://leetcode.com/problems/3sum-closest/ Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three

原题地址 Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not