潇潇雨歇的专栏

Given an integer n, return the number of trailing zeroes in n!.Note: Your solution should be in logarithmic time complexity. 分析:有人可能第一反应就是现求出N!,然后再根据求出的结果，最后得出N!的末尾有多少个0。但是转念一想，会不会溢出

Implement strStr().Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.My C++ solution！ int strStr(string haystack, string needle)

Write a function that takes an unsigned integer and returns the number of ’1' bits it has (also known as the Hamming weight).For example, the 32-bit integer ’11' has binary representation 000000

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

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

Rotate an array of n elements to the right by k steps.For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].Note:Try to come up as many solutions as yo

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.My C++ solution！/**

Write an algorithm to determine if a number is "happy".A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares

Given a collection of numbers that might contain duplicates, return all possible unique permutations.For example,[1,1,2] have the following unique permutations:[1,1,2], [1,2,1], and [2,1

Reverse bits of a given 32 bits unsigned integer.For example, given input 43261596 (represented in binary as 00000010100101000001111010011100), return 964176192 (represented in binary as0011100101

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.You may assume no duplicates in the array.

Given a collection of numbers, return all possible permutations.For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].中文描述：将数组实现全排列

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.我的C++代码！struct ListNode {

题目描述题目一：写一个函数，输入n，求斐波那契数列的第n项。斐波那契数列定义如下：

首先统一链表的数据结构为：struct ListNode { int val; struct ListNode *next; ListNode(int x) :val(x), next(NULL) {}};题目一：从尾到头打印链表：输入一个链表，从尾到头打印链表每个节点的值。分析：难点在于链表只有指向后继的指针，没有指向前驱的指针。转换思路，结合栈后

题目：在字符串中找出第一个只出现一次的字符，如输入”abaccdeff“，则输出‘b’分析：题目中要求第一个只出现一次的字符，那么就跟字符出现的次数有关。我们考虑如何统计字符出现的次数，然后找出第一个次数为1的那个字符。这里我们需要一个数据容器来保存字符出现次数，并且能够通过字符找出其相对应的次数。哈希表就是一种常用用的容器。我们可以定义哈希表的键值(Key)是字符的A

面试题：给定字符串，删除开始和结尾处的空格，并将中间的多个连续的空格合并成一个void RemoveExtraSpace(char* str){ bool keep_space = false; int new_str_end = 0; for (int i = 0; str[i]; ++i) { //如果遍历得到的此字符不是空格，则将标志

Reverse a singly linked list.Hint:A linked list can be reversed either iteratively or recursively. Could you implement both?My C++ solution！/** * Definition for singly-linked list. * struc

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?My C++ solut

Implement atoi to convert a string to an integer.Hint: Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input ca

Determine whether an integer is a palindrome. Do this without extra space.My C++ solution！int reverse(int integer){ if(integer==0x80000000) return 0; long long temp=0; int len=0; bool flag=

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.The brackets must close in the correct order, "()" and "()[]{}" are all va

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.M

Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating letters for "abcabcbb" is "abc", which the length is 3. Fo

Given a linked list, remove the nth node from the end of list and return its head.For example, Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the

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

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.My C++ solution！ListNode* mergeTwoLists(ListNode* l1,

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a link

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

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

Remove all elements from a linked list of integers that have value val.ExampleGiven: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6Return: 1 --> 2 --> 3 --> 4 --> 5My C++ solution！/*

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 add

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.My C++ solution!

Given an array of integers, find if the array contains any duplicates. Your function should return true if any value appears at least twice in the array, and it should return false if every element

Given two binary strings, return their sum (also a binary string).For example,a = "11"b = "1"Return "100".My C++ solution！string addBinary(string a, string b) { int len_a

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]]My C++ solution！vect

二叉树中的面试题比较常见的题型大概有下面几个：创建一颗二叉树（先序，中序，后序）、遍历一颗二叉树（先序，中序，后序和层次遍历）、求二叉树中叶子节点的个数、求二叉树的高度、求二叉树中两个节点的最近公共祖先、打印和为某一值的全部路径、求某一节点是否在一个树中等等。再详细的说这些面试题之前，不妨先看一下几种常见的二叉树：完全二叉树：若二叉树的高度是h，除第h层之外，其他（1~h-1）层的