chen52671的专栏

Given an array of size n, find the majority element. The majority element is the element that appears more than ⌊ n/2 ⌋ times.You may assume that the array is non-empty and the majority element

Write a function to remove duplicated objects from an array. Preserve the order. For example, if the input array is [1, 5, 4, 2, 7, 2, 6, 5], the result should be [1, 5, 4, 2, 7, 6]. The implementation

Given a sorted array, remove the duplicates in place such that each element appear only once and return the new length.Do not allocate extra space for another array, you must do this in place with cons

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. 给你2个排序好的单链表，返回一个merge的单链表。 链表数据结构： public class ListNode

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.public int

Reverse digits of an integer.Example1: x = 123, return 321 Example2: x = -123, return -321click to show spoilers.Have you thought about this? Here are some good questions to ask before coding. Bonus

Implement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.Update (2014-11-02): The signature of the function had been updated to retur

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 f

Related to question Excel Sheet Column TitleGiven a column title as appear in an Excel sheet, return its corresponding column number.For example: A -> 1 B -> 2 C -> 3 ...

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. * Definition for binary tree

You are climbing a stair case. It takes n steps to reach to the top.Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?   public int climbStairs(in

Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical and the nodes have the same value.还是用d

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

Given a sorted linked list, delete all duplicates such that each element appear only once.For example,Given 1->1->2, return 1->2.Given 1->1->2->3->3, return 1->2->3.  public class ListNode

public class SingleNumberII { /* * Given an array of integers, every element appears three times except for * one. Find that single one. * * Note: Your algorithm should have a

Given an input string, reverse the string word by word.For example, Given s = “the sky is blue”, return “blue is sky the”.Update (2015-02-12): For C programmers: Try to solve it in-place in O(1) spa

public class PopulatingNextRightPointersinEachNode { /* * Given a binary tree * * struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; * TreeLinkNode *next; } Populate

The count-and-say sequence is the sequence of integers beginning as follows: 1, 11, 21, 1211, 111221, …1 is read off as “one 1” or 11. 11 is read off as “two 1s” or 21. 21 is read off as “one 2, the

Given a string s consists of upper/lower-case alphabets and empty space characters ’ ‘, return the length of last word in the string.If the last word does not exist, return 0.Note: A word is defined as

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.给你一个整形数组，该数组实际表示一个非负整数，每个元素代表

Given an integer n, return the number of trailing zeroes in n!.Note: Your solution should be in logarithmic time complexity.Credits:Special thanks to @ts for adding this problem and creating

Given a positive integer, return its corresponding column title as appear in an Excel sheet.For example: 1 -> A 2 -> B 3 -> C ... 26 -> Z 27 -> AA 28 -> AB Tag:Mat

Compare two version numbers version1 and version1.If version1 > version2 return 1, if version1 version2 return -1, otherwise return 0.You may assume that the version strings are non-empty and

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 ↘

Given an array of integers, every element appears twice except for one. Find that single one.Note:Your algorithm should have a linear runtime complexity. Could you implement it without using ext

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]]Hide Tags Array

Given an index k, return the kth row of the Pascal's triangle.For example, given k = 3,Return [1,3,3,1].Note:Could you optimize your algorithm to use only O(k) extra space?和上一题类似，给一个

Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.For example:Given the below binary tree and 

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.For example,"A man, a plan, a canal: Panama" is a palindrome."race a car" is not a

Validate if a given string is numeric.Some examples:"0" => true" 0.1 " => true"abc" => false"1 a" => false"2e10" => trueNote: It is intended for the problem statement to be ambiguo

Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never diffe

Given two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100”.public class Solution {    public String addBinary(String a, String b) {

Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree {3,9,20,#,#,15,7}, 3 / \ 9 20

The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)P A H NA P L S I

Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.public int minDepth(TreeNode root)

Given a binary tree, return the bottom-up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For example:Given binary tree {3,9,20,#,#,15,7}, 

给一个数组，还有一个target，找到数组中能够产生和值为target的两个数，返回2个数的index。 假设每次输入，肯定有唯一解 2次for循环得出一个暴力解，但是超时了。 或者空间换时间，把每一个数对应需要的另一个值保存在hashmap中，然后再来一次循环，如果包含该key，就对了“`java /* * Given an array of integers, find t