题目描述: There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle e…

319. Bulb Switcher My Submissions QuestionEditorial Solution Total Accepted: 15915 Total Submissions: 39596 Difficulty: Medium There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the thi…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle every i…

有n盏关着的灯,第k轮把序号为k倍数的关着的灯打开,开着的灯关闭. class Solution { public: int bulbSwitch(int n) { return (int)sqrt(n*1.0); } };…

智商压制的一道题 这个题有个数学定理: 一般数(非完全平方数)的因子有偶数个 完全平凡数的因子有奇数个 开开关的时候,第i个灯每到它的因子一轮的时候就会拨动一下,也就是每个灯拨动的次数是它的因子数 而拨动偶数次是关,拨动奇数次是开 现在就是求哪些数的因子有奇数个,也就是求n以内的完全平凡数 这里又有一个定理: n以内的完全平方数个数是sprt(n) 所以代码很简单 public int bulbSwitch(int n) { return (int)Math.sqrt(n); }…

[LeetCode]319. Bulb Switcher 解题报告(Python) 标签(空格分隔): LeetCode 题目地址:https://leetcode.com/problems/bulb-switcher/description/ 题目描述: There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the t…

题目: There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle eve…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle every i…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the i-th round, you toggle every …

初始时有 n 个灯泡关闭. 第 1 轮,你打开所有的灯泡. 第 2 轮,每两个灯泡切换一次开关. 第 3 轮,每三个灯泡切换一次开关(如果关闭,则打开,如果打开则关闭).对于第 i 轮,你每 i 个灯泡切换一次开关. 对于第 n 轮,你只切换最后一个灯泡的开关. 找出 n 轮后有多少个亮着的灯泡.示例:给定 n = 3.状态off表示灯泡关闭,on表示开启.初始时, 灯泡状态 [off, off, off].第一轮后, 灯泡状态 [on, on, on].第二轮后, 灯泡状态 [on, off,…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the nth round, you only toggle th…

There is a room with n lights which are turned on initially and 4 buttons on the wall. After performing exactly m unknown operations towards buttons, you need to return how many different kinds of status of the n lights could be. Suppose n lights are…

Bulb Switcher There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you…

There is a room with n lights which are turned on initially and 4 buttons on the wall. After performing exactly m unknown operations towards buttons, you need to return how many different kinds of status of the n lights could be. Suppose n lights are…

变换灯泡颜色 There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the nth round, you only to…

问题描述: There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the nth round, you only tog…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the nth round, you only toggle th…

题目描述: There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle e…

319. 灯泡开关 初始时有 n 个灯泡关闭. 第 1 轮,你打开所有的灯泡. 第 2 轮,每两个灯泡你关闭一次. 第 3 轮,每三个灯泡切换一次开关(如果关闭则开启,如果开启则关闭).第 i 轮,每 i 个灯泡切换一次开关. 对于第 n 轮,你只切换最后一个灯泡的开关. 找出 n 轮后有多少个亮着的灯泡. 示例: 输入: 3 输出: 1 解释: 初始时, 灯泡状态 [关闭, 关闭, 关闭]. 第一轮后, 灯泡状态 [开启, 开启, 开启]. 第二轮后, 灯泡状态 [开启, 关闭, 开启]. 第…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 日期 题目地址:https://leetcode.com/problems/bulb-switcher-ii/description/ 题目描述 There is a room with n lights which are turned on initially and 4 buttons on the wall. After performing…

小二终于开通博客了,真是高兴.最近在看Java,所以就拿leetcode练练手了.以后我会将自己解体过程中的思路写下来,分享给大家,其中有我自己原创的部分,也有参考别人的代码加入自己理解的部分,希望大家看了多提意见,一块加油. 问题描述: Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the i-th round, you toggle every …

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle every i…

There are n bulbs that are initially off. You first turn on all the bulbs. Then, you turn off every second bulb. On the third round, you toggle every third bulb (turning on if it's off or turning off if it's on). For the ith round, you toggle every i…

题目描述: 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…

题目描述: 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 shoul…

问题描述: Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero. Note: Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c) The…

题目描述: Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)…

There is a room with n lights which are turned on initially and 4 buttons on the wall. After performing exactly munknown operations towards buttons, you need to return how many different kinds of status of the n lights could be. Suppose n lights are…

题目描述: Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1. Examples: s = "leetcode" return 0. s = "loveleetcode", return 2. 解题思路: 开个26个数的数组,然后先对字符串过一遍,统计每个字母出现的次数,然后从头再国一遍,…