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> #…

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…