1.1 Implement an algorithm to determine if a string has all unique characters. What if you cannot use additional data structures? 字符串问题,需要先确定是不是只有ASCII码. 如果是,可以用char[256],也可以用位向量.位向量的实现参照<编程珠玑>.i&MASK就是取余.i>>SHIFT就是取商. class BitVector { pu…

3.1 Describe how you could use a single array to implement three stacks. Flexible Divisions的方案,当某个栈满了之后,需要把相邻的栈调整好,这是一个递归的过程. 每个stack有一些属性,所以不妨将每个stack封闭起来,我这里是用一个private的struct来实现,方便,同时对外部又不可见. 对于一些常用的操作,比如环形数组取下一个数,前一个数,都可以封装起来. class XNStack { pub…

链表的题里面,快慢指针.双指针用得很多. 2.1 Write code to remove duplicates from an unsorted linked list.FOLLOW UPHow would you solve this problem if a temporary buffer is not allowed? 2.2 Implement an algorithm to find the kth to last element of a singly linked list.…

8.2 Imagine you have a call center with three levels of employees: respondent, manager, and director. An incoming telephone call must be first allocated to a respondent who is free. If the respondent can't handle the call, he or she must escalate the…

7.4 Write methods to implement the multiply, subtract, and divide operations for integers. Use only the add operator. 比较简单.但是要封装得好. 7.5 Given two squares on a two-dimensional plane, find a line that would cut these two squares in half. Assume that th…

9.1 You are given two sorted arrays, A and B, and A has a large enough buffer at the end to hold B. Write a method to merge B into A in sorted order. A has enough buffer at the end to hold B, we can merge two arrays from end to start index, like merg…

1.Implement an algorithm to determine if a string has all unique characters What if you can not use additional data structures? The length of ACSII code of a character is 8, so we can build a array, the length is 260, to represent the hash table of a…

struct TreeNode{ int val; TreeNode* left; TreeNode* right; TreeNode(int val):val(val),left(NULL),right(NULL){} }; Not all binary trees are binary search trees. 4.1 Implement a function to check if a tree is balanced. For the purposes of this question…

6.2 There is an 8x8 chess board in which two diagonally opposite corners have been cut off. You are given 31 dominos, and a single domino can cover exactly two squares. Can you use the 31 dominos to cover the entire board? Prove your answer (byprovid…

5.1 You are given two 32-bit numbers, N andM, and two bit positions, i and j. Write a method to insert M into Nsuch that M starts at bit j and ends at bit i. You can assume that the bits j through i have enough space to fit all ofM. That is, ifM= 100…

二叉查换树,左孩子小于等于根,右孩子大于根. 完全二叉树,除最后一层外,每一层上的节点数均达到最大值:在最后一层上只缺少右边的若干结点. complete binary tree 满二叉树,完美二叉树是全部结点数达到最大的二叉树.perfect binary tree, full binary tree. 平衡二叉树,左右子树的高度在一定范围内. 二叉查找树(Binary Search Tree),也称二叉搜索树.有序二叉树(ordered binary tree),排序二叉树(sorted b…

Oh, no! You have just completed a lengthy document when you have an unfortu- nate Find/Replace mishap. You have accidentally removed all spaces, punctuation, and capitalization in the document. A sentence like "I reset the computer. It still didn't b…

18.1 Write a function that adds two numbers. You should not use + or any arithmetic operators. 这道题让我们实现两数相加,但是不能用加号或者其他什么数学运算符号,那么我们只能回归计算机运算的本质,位操作Bit Manipulation,我们在做加法运算的时候,每位相加之后可能会有进位Carry产生,然后在下一位计算时需要加上进位一起运算,那么我们能不能将两部分拆开呢,我们来看一个例子759+674 1.…

17.2 Design an algorithm to figure out if someone has won a game oftic-tac-toe. 这道题让我们判断玩家是否能赢井字棋游戏,有下面几点需要考虑: 1. 判断是否能赢hasWon函数是调用一次还是多次,如果是多次,我们可能为了优化而需要加入一些预处理. 2. 井字棋游戏通常是3x3的大小,我们是否想要实现NxN的大小? 3. 我们需要在代码紧凑,执行速度和代码清晰之间做出选择. #include <iostream> #…

CHAPTER 2 Recipe 2-1. Initializing Variables Recipe 2-2. Initializing Objects with Initializer Lists 使用初始化列表的使用 Recipe 2-3. Using Type Deduction 关于auto关键字的使用 Recipe 2-4. Using auto with Functions Recipe 2-5. Working with Compile Time Constants conste…

Chapter 1. Arrays and Strings 1.1 Unique Characters of a String 1.2 Reverse String 1.3 Permutation String 1.4 Replace Spaces 1.5 Compress String 1.6 Rotate Image 1.7 Set Matrix Zeroes 1.8 String Rotation Chapter 2. Linked Lists 2.1 Remove Duplicates…

前面两片文章讲解了通过AIDL和Messenger两种方式实现Android IPC.而本文所讲的并不是第三种IPC方式,而是对前面两种方式进行封装,这样我们就不用直接把Aidl文件,java文件拷贝到客户端了,而是为客户端提供一个aar(Anroid Archive)包.通过这个aar包对AIDL或者Messenger进行封装,最终客户端就可以像调用一般的java类一样,而不用处理通信方面的内容.(实际上书中说是要打包成jar包,但是在新建的Java Library Module中,我没能成功…

Messenger类实际是对Aidl方式的一层封装.本文只是对如何在Service中使用Messenger类实现与客户端的通信进行讲解,对Messenger的底层不做说明.阅读Android Programming: Pushing the Limits -- Chapter 7:Android IPC -- AIDL了解如何使用Aidl的方式实现服务端与客户端的通信. 在Service中使用Messenger,大部分代码还是跟Android的消息机制打交道,具体一点就是跟Handler,Mes…

18.12 Given an NxN matrix of positive and negative integers, write code to find the submatrix with the largest possible sum. 这道求和最大的子矩阵,跟LeetCode上的Maximum Size Subarray Sum Equals k和Maximum Subarray很类似.这道题不建议使用brute force的方法,因为实在是不高效,我们需要借鉴上面LeetCode…

18.11 Imagine you have a square matrix, where each cell (pixel) is either black or white. Design an algorithm to find the maximum subsquare such that all four borders are filled with black pixels. LeetCode上的原题,请参见我之前的解法Maximal Square.书上给了两种解法,但是比较长:…

18.10 Given two words of equal length that are in a dictionary, write a method to transform one word into another word by changing only one letter at a time. The new word you get in each step must be in the dictionary. 这道题让我们将一个单词转换成另一个单词,每次只能改变一个字母,…

18.9 Numbers are randomly generated and passed to a method. Write a program to find and maintain the median value as new values are generated. LeetCode上的原题,请参见我之前的博客Find Median from Data Stream. 解法一: priority_queue<int> small; priority_queue<int,…

18.8 Given a string s and an array of smaller strings T, design a method to search s for each small string in T. 这道题给我们一个字符串s,和一个字符串数组T,让我们找T中的每一个小字符串在s中出现的位置,这道题很适合用后缀树Suffix Tree来做,LeetCode中有几道关于前缀树(Prefix Tree, Trie)的题,Implement Trie (Prefix Tree)…

5.7 Given a list of words, write a program to find the longest word made of other words in the list. 这道题给了我们一个字符串数组,让我们找到最长的那个单词是由字符串数组中的其他单词组成的,LeetCode上跟类似的题目有Word Break和Word Break II.那么我们首先来想如果是拆分两个单词怎么做,那我们要首先把所有的单词存到哈希表里,然后遍历每个单词,每个位置上都拆分成左右两个字符…

18.6 Describe an algorithm to find the smallest one million numbers in one billion numbers. Assume that the computer memory can hold all one billion numbers. 这道题让我们在十亿个数字中找到最小的一百万个数字,而且限定了计算机只有能存十亿个数字的内存.这题有三种解法,排序,最小堆,和选择排序. 首先来看排序方法,这种方法简单明了,就是把这十亿…

18.5 You have a large text file containing words. Given any two words, find the shortest distance (in terms of number of words) between them in the file. If the operation will be repeated many times for the same file (but different pairs of words), c…

18.4 Write a method to count the number of 2s between 0 and n. 这道题给了我们一个整数n,让我们求[0,n]区间内所有2出现的个数,比如如果n=20,那么满足题意的是2, 12, 20,那么返回3即可.LeetCode上有一道很类似的题Factorial Trailing Zeroes,但是那道题求5的个数还包括了因子中的5,比如10里面也有5,这是两题的不同之处.那么首先这题可以用brute force来解,我们对区间内的每一个数字…

18.3 Write a method to randomly generate a set of m integers from an array of size n. Each element must have equal probability of being chosen. 这道题让我们从一个数组中随机取出m个数字,要求每个数字被取出的概率相同,其实这道题用的是之前那道18.2 Shuffle Cards的方法,同样我们可以用递归和迭代两种方法来做,递归的思路还用的回溯法,回溯到i+…

18.2 Write a method to shuffle a deck of cards. It must be a perfect shuffle—in other words, each of the 52! permutations of the deck has to be equally likely. Assume that you are given a random number generator which is perfect. 这道题让我们实现一个洗牌的算法,实际上洗…

17.14 Oh, no! You have just completed a lengthy document when you have an unfortunate Find/Replace mishap. You have accidentally removed all spaces, punctuation, and capitalization in the document. A sentence like "I reset the computer. It still didn…