这是在看geeksforgeeks时看到的一道题,挺不错的,题目是 Given a number system with only 3 and 4. Find the nth number in the number system. First few numbers in the number system are: 3, 4, 33, 34, 43, 44, 333, 334, 343, 344, 433, 434, 443, 444, 3333, 3334, 3343, 3344, 343…

Strobogrammatic Number A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to determine if a number is strobogrammatic. The number is represented as a string. For example, the nu…

odd number 奇数 even number 偶数…

最近在优化一个页面时候.IDEA 提示我错误的使用了包装类.当时感觉很诧异. 随后.我上Stack Overflow上面查了一下,终于发现了问题所在. new Number('123') 与 Number('123') 是有很大区别的. 具体来说就是:new Number('123') 会返回一个包装过的对象,类似于Java中的Integer类型,而 Number('123') 会返回一个原始的数字类型,相当于Java中的int类型.虽然内容相等,但是在后面判断时,可能会产生误解. 随后我在Ch…

ES6在Number对象上,新提供了Number.isFinite()和Number.isNaN()两个方法,用来检查Infinite和NaN这两个特殊值. Number.isFinite()用来检查一个数值是否非无穷(infinity). Number.isFinite(15); // true Number.isFinite(0.8); // true Number.isFinite(NaN); // false Number.isFinite(Infinity); // false Num…

在回答园子问题的时候发现了不少新东西,写下来分享一下 == 下面的图就是此篇的概览,另外文章的解释不包括ES6新增的Symbol,话说这货有包装类型,但是不能new... 基于JS是面向对象的,所以我们称呼function为“方法”,等同于“函数”. 1.Number与Number Object ——原始类型与包装类型(primitive VS wrapper object) ECMAScript定义了7种数据类型:6种原始类型(ES6新增Symbol)以及Object.原始类型(primiti…

how to convert a number to a number array in javascript without convert number to a string 如何在不将数字转换为一个字符串的情况下将一数字转换为javascript中的一个数字数组 Number To Array Math.round 四舍五入 bug "use strict"; /** * * @author xgqfrms * @license MIT * @copyright xgqfrms…

http://acm.sdut.edu.cn/sdutoj/problem.php?action=showproblem&problemid=2609 数位DP 以前没怎么做过,自己憋了半天,还是看了标程,标程写的就是好呀. 相关注释见代码: #include<iostream> #include<cstdio> #include<vector> #include<stack> #include<cstring> #include<…

简介: 使用位移法将ip转为number型以及将number型转为ip,使用语言为python2.7 #!/usr/bin/env python # coding:utf-8 def ip2num(ip):     ip = [int(x) for x in ip.split('.')]     return ip[0] << 24 | ip[1] << 16 | ip[2] << 8 | ip[3] print ip2num('10.101.101.13') #174…

看MDN Beginners文档的时候注意到了这种用法 var n1 = Number(123); , 冒出的第一个疑问就是和 var n2 = new Number(123); 有什么区别呢? 首先用typeof做下探测, n1是number而n2是object, 他们的本质区别就是type不同. 那么有趣的问题来了, Number内部肯定知道是怎么调用的它, 那是怎么实现的呢? 最先想到的就是根据caller来区分, 但在实验的过程中发现两个问题: 全局调用的时候没有caller 就算知道c…

leetcode 136. Single Number 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? 解题思路: 如果以线性复杂度和…

136. Single Number Given an array of integers, every element appears twice except for one. Find that single one. (Easy) Note:Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? 分析: 第一问属于技巧题,做过就会,…

公司项目使用了iview2.0版本的,有一个需求是需要把里面的值换成number类型并且校验,代码大致如下,使用了v-modal.number来实现转换, <FormItem label="学号" prop="name"> <Input v-model.number=" Student.Sno" placeholder="Enter name"></Input> </FormItem&…

▶ 三个与丑数相关的问题 ▶ 第 263题,判定一个数字是否是丑数,即其素因子是否仅由 2,3,5 构成. ● 常规消除判别,4 ms class Solution { public: bool isUgly(int num) { ) return false; ); num /= ); ); num /= ); ); num /= ); ; } }; ● 递归方法,6 ms class Solution { public: bool isUgly(int num) { ) return fal…

[] Given an array of integers, every element appears twice except for one. Find that single one. [] Given an array of integers, every element appears three times except for one. Find that single one. (better solution is needed) Note: Your algorithm s…

Write a program to find the nth super ugly number. Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of sizek. For example, [1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32] is the sequence of the first 12 s…

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"…

A strobogrammatic number is a number that looks the same when rotated 180 degrees (looked at upside down). Write a function to determine if a number is strobogrammatic. The number is represented as a string. For example, the numbers "69", "…

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 of its digits, and repeat the process until the…

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? 本来是一道非常简单的题,但是由于加上了时间复杂度必须是O(n),并且空间复杂度为O(1)…

The kth great number Time Limit:1000MS     Memory Limit:65768KB     64bit IO Format:%I64d & %I64u Submit Status Practice HDU 4006 Description Xiao Ming and Xiao Bao are playing a simple Numbers game. In a round Xiao Ming can choose to write down a nu…

Number(): 概述:Number 对象由 Number() 构造器创建,是经过封装的能让你处理数字值的对象.在非构造器上下文中 (如:没有 new 操作符),Number 能被用来执行类型转换. 语法:Number(value); 特点: 1.如果是Boolean值,true和false值将分别被转换为1和0. 2.如果是数字值,只是简单的传入和返回. 3.如果是null值,返回0. 4.如果是undefined,返回NaN. 5.如果是字符串:  a.  如果字符串中只包含数字时,将其转…

题目简述 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 of its digits, and repeat the process unti…

Given an array of integers, the majority number is the number that occurs more than half of the size of the array. Find it. Notice You may assume that the array is non-empty and the majority number always exist in the array. Have you met this questio…

1.属性NaN的误解纠正 NaN (Not a Number)在w3c 中定义的是非数字的特殊值 ,它的对象是Number ,所以并不是任何非数字类型的值都会等于NaN,只有在算术运算或数据类型转换出错时是NaN[说明某些算术运算(如求负数的平方根)的结果不是数字.方法 parseInt() 和 parseFloat() 在不能解析指定的字符串时就返回这个值NaN.对于一些常规情况下返回有效数字的函数,也可以采用这种方法,用 Number.NaN 说明它的错误情况].NaN 与其他数值进行比较的…

hihoCoder #1432 : JiLi Number(吉利数) 时间限制:1000ms 单点时限:1000ms 内存限制:256MB Description - 题目描述 Driver Ji likes the digit "1". He has an accumulator which shows the sum of input number. He lists all of positive number no more than N and starts counting…

Number类型的值:整数/浮点数值 整数 十进制  e.g.: var intNum = 50; 八进制  (严格模式下无效,解析错误)字面值首位必须是0,之后的数字序列为0-7  e.g.: var intNum = 070; //解析为十进制56 (如果字面值数值超出了范围,前导0将被忽略,后面的数值将被当做十进制数值解析 e.g.: var intNum = 078; //无效的八进制数字,解析为十进制78) 十六进制  字面值的前两位必须是0x(或0X),之后的数据序列为0~7或A~F…