Single Number Given an array of integers, every element appears twice except for one. Find that single one. def singleNumber(self, A): l = len(A) if l < 2: return A[0] A.sort() for i in range(0,l-1,2): if A[i] != A[i+1]: return A[i] return A[l-1] 思路:…

视频分析: http://v.youku.com/v_show/id_XMTMyODkyNDA0MA==.html?from=y1.7-1.2 class Solution(object): def isHappy(self, n): if n==1: return True elif n==4: return False else: return self.isHappy(self.Happy(n)) def Happy(self,n): z=0 while n!=0: d=n%10 z+=p…

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by…

Given n nodes labeled from 0 to n - 1 and a list of undirected edges (each edge is a pair of nodes), write a function to find the number of connected components in an undirected graph. Example 1: 0        3 |          | 1 --- 2    4 Given n = 5 and e…

版权声明: 本文为博主Bravo Yeung(知乎UserName同名)的原创文章,欲转载请先私信获博主允许,转载时请附上网址 http://blog.csdn.net/lzuacm. C#版 - Leetcode 191. Number of 1 Bits题解 191. 位1的个数 在线提交: https://leetcode-cn.com/problems/number-of-1-bits/description/ 题目描述 编写一个函数,输入是一个无符号整数,返回其二进制表达式中数字位数为…

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by…

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. Count the number of distinct island…

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. Count the number of distinct island…

Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water. Count the number of distinct island…

Leetcode ugly number set (3 now) new ugly number is generated by multiplying a prime with previous generated ugly numbe Is ugly number or not class Solution { public boolean isUgly(int num) { if(num==0) return false; //how to generate the number whil…

A 2d grid map of m rows and n columns is initially filled with water. We may perform an addLand operation which turns the water at position (row, col) into a land. Given a list of positions to operate, count the number of islands after each addLand o…

Given a positive integer, output its complement number. The complement strategy is to flip the bits of its binary representation. 給一個正整數,算出他的二補數 (2's complement). 二補數就是將該數字的二進制碼全部翻轉過來. Note: The given integer is guaranteed to fit within the range of…

原题地址:http://oj.leetcode.com/problems/single-number-ii/ 题意:Given an array of integers, every element appears three times except for one. Find that single one. 要求:和single number一样,线性时间复杂度,不能使用额外空间. 解题思路:这道题就比较难了.也是考察位操作.网上的位操作解法看了好半天也没有得其精髓.由于序列中除了那唯一的…

原题地址:http://oj.leetcode.com/problems/valid-number/ 题意:判断输入的字符串是否是合法的数. 解题思路:这题只能用确定有穷状态自动机(DFA)来写会比较优雅.本文参考了http://blog.csdn.net/kenden23/article/details/18696083里面的内容,在此致谢! 首先这个题有9种状态: 0初始无输入或者只有space的状态1输入了数字之后的状态2前面无数字,只输入了dot的状态3输入了符号状态4前面有数字和有do…

#question : 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 extra memory? class Solution(object): def si…

class Solution(object): def isPalindrome(self, x): """ :type x: int :rtype: bool """ if x < 0: return False x=str(x) i=0 j=len(x)-1 while i < j: if x[i] != x[j]: return False i+=1 j-=1 return True…

1.用双重循环逐个遍历(超时) 2.用list B的append和remove函数(超时) 3.用dict B(AC) class Solution: # @param A, a list of integer # @return an integer def singleNumber(self, A): B = {} for i in A: if i not in B: B[i] = 1 else: B[i] = 2 for i in B: if B[i] == 1: ret = i brea…

一次AC 题目要求中有空间限制,因此没有采用字符串由量变向中间逐个对比的方法,而是采用计算翻转之后的数字与x是否相等的方法: class Solution: # @return a boolean def isPalindrome(self, x): o = x ret = 0 flag = 1 if x < 0: return False while(x!=0): ret = ret*10+x%10 x = x/10 return ret == o…

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 00000000000000000000000000001011, so the function should retu…

Given a grid where each entry is only 0 or 1, find the number of corner rectangles. A corner rectangle is 4 distinct 1s on the grid that form an axis-aligned rectangle. Note that only the corners need to have the value 1. Also, all four 1s used must…

There are a number of spherical balloons spread in two-dimensional space. For each balloon, provided input is the start and end coordinates of the horizontal diameter. Since it's horizontal, y-coordinates don't matter and hence the x-coordinates of s…

We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I'll tell you whether the number I picked is higher or lower. However, when you guess a particula…

We are playing the Guess Game. The game is as follows: I pick a number from 1 to n. You have to guess which number I picked. Every time you guess wrong, I'll tell you whether the number is higher or lower. You call a pre-defined API guess(int num) wh…

Additive number is a positive integer whose digits can form additive sequence. A valid additive sequence should contain at least three numbers. Except for the first two numbers, each subsequent number in the sequence must be the sum of the preceding…

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array. For example, Given nums = [0, 1, 3] return 2. Note: Your algorithm should run in linear runtime complexity. Could you implement it u…

Write a program to find the n-th ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 1, 2, 3, 4, 5, 6, 8, 9, 10, 12 is the sequence of the first 10 ugly numbers. Note that 1 is typically treated as an…

Write a program to check whether a given number is an ugly number. Ugly numbers are positive numbers whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7. Note that 1 is ty…

Given an array of numbers nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. For example: Given nums = [1, 2, 1, 3, 2, 5], return [3, 5]. Note: The order…

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to count the total strobogrammatic numbers that exist in the range of low <= num <= high. For example,Given low = "50&qu…

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Find all strobogrammatic numbers that are of length = n. For example,Given n = 2, return ["11","69","88","96"…