1 题目 Description: Count the number of prime numbers less than a non-negative number, n. 接口:public int countPrimes(int n); 2 思路 统计小于n的素数个数,注意不包括n. 思路1:素数的判断 很容易想到素数的判断isPrime,然后逐个数来进行判断是否是素数.进行统计,输出结果. 复杂度: 把isPrime时间复杂度控制在O(n^0.5)的话,因此:Time:O(n^1.5)…

leetcode面试准备: Maximal Rectangle 1 题目 Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area. 接口: int maximalRectangle(char[][] matrix) 2 思路 这是一道非常综合的题目,要求在0-1矩阵中找出面积最大的全1矩阵.刚看到这道题会比较无从下手,b…

leetcode面试准备: Game of Life 1 题目 According to the Wikipedia's article: "The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970." Given a board with m by n cells, each c…

leetcode面试准备: Word Pattern 1 题目 Given a pattern and a string str, find if str follows the same pattern. Examples: pattern = "abba", str = "dog cat cat dog" should return true. pattern = "abba", str = "dog cat cat fish&qu…

leetcode面试准备:Add and Search Word - Data structure design 1 题目 Design a data structure that supports the following two operations: void addWord(word) bool search(word) search(word) can search a literal word or a regular expression string containing on…

leetcode面试准备:Reverse Words in a String 1 题目 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…

leetcode面试准备:Implement Trie (Prefix Tree) 1 题目 Implement a trie withinsert, search, and startsWith methods. Note: You may assume that all inputs are consist of lowercase letters a-z. 2 思路 该题是实现trie树. Trie,又称单词查找树或键树,是一种树形结构.典型应用是用于统计和排序大量的字符串(但不仅限于字符…

leetcode面试准备:Triangle 1 题目 Given a triangle, find the minimum path sum from top to bottom. Each step you may move to adjacent numbers on the row below. For example, given the following triangle [ [2], [3,4], [6,5,7], [4,1,8,3] ] The minimum path sum…

leetcode面试准备:Sliding Window Maximum 1 题目 Given an array nums, there is a sliding window of size k which is moving from the very left of the array to the very right. You can only see the k numbers in the window. Each time the sliding window moves righ…

leetcode面试准备:Simplify Path 1 题目 Given an absolute path for a file (Unix-style), simplify it. For example, path = "/home/", => "/home" path = "/a/./b/../../c/", => "/c" Corner Cases: Did you consider the case w…