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 每次遍历索引 字典保存索引 蓄水池抽样 日期 题目地址:https://leetcode.com/problems/random-pick-index/description/ 题目描述 Given an array of integers with possible duplicates, randomly output the index of…

Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number must exist in the array. Note: The array size can be very large. Solution that uses too much extra sp…

我是链接 看到这道题,想到做的几道什么洗牌的题,感觉自己不是很熟,但也就是rand()函数的调用,刚开始用map<int, vector<int >>来做,tle,后来就想着直接保存nums数组,和每个元素的数目,然后先生成一个随机的第几个target,然后从nums里面再找这个index,交了,就过了,有套路么? class Solution { public: map<int, int> m; vector<int> num; Solution(vect…

Question 398. Random Pick Index Solution 思路:重点是如果数据中有多个数target相等,要从这些数中随机取一个,根据例题 假设输入是: int[] nums = new int[]{1, 2, 3, 3, 3}; int target = 3; 模拟: 1 != target pass 2 != target pass 3 == target pick的概率 nextInt(1)==0的概率 1,返回这个index的概念是1 - 1/3 -1/3 = 1…

随机返还target值的坐标(如果存在多个target). 不太明白为什么这个题是M难度的. 无非是要么弄TABLE之类的,开始麻烦点,但是pick的时候直接PICK出来就行了. 要么开始简单点,都存了,选的时候再随机选. 前者各种溢出..貌似memory在leetcode比较值钱..就用后者 public class Solution { int[] nums; public Solution(int[] nums) { this.nums = nums; } public int pick(…

［抄题］: Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number must exist in the array. Note:The array size can be very large. Solution that uses too much ext…

Given an array of integers with possible duplicates, randomly output the index of a given target number. You can assume that the given target number must exist in the array. Note:The array size can be very large. Solution that uses too much extra spa…

给定一个可能含有重复元素的整数数组,要求随机输出给定的数字的索引. 您可以假设给定的数字一定存在于数组中.注意:数组大小可能非常大. 使用太多额外空间的解决方案将不会通过测试.示例:int[] nums = new int[] {1,2,3,3,3};Solution solution = new Solution(nums);// pick(3) 应该返回索引 2,3 或者 4.每个索引的返回概率应该相等.solution.pick(3);// pick(1) 应该返回 0.因为只有nums[…

作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/unique-paths/description/ 题目描述: A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below). The robot can only move either…

[LeetCode]880. Decoded String at Index 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/decoded-string-at-index/description/ 题目描述: An encoded string S is given. To find and wri…

[LeetCode]376. Wiggle Subsequence 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址: https://leetcode.com/problems/wiggle-subsequence/description/ 题目描述: A sequence of numbers is called a wiggle sequence if the differences betw…

[LeetCode]649. Dota2 Senate 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/dota2-senate/description/ 题目描述: In the world of Dota2, there are two parties: the Radiant and the Dire. The Dota2 sena…

[LeetCode]911. Online Election 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/online-election/description/ 题目描述: In an election, the i-th vote was cast for persons[i] at time times[i]. Now, we…

[LeetCode]886. Possible Bipartition 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/possible-bipartition/description/ 题目描述: Given a set of N people (numbered 1, 2, ..., N), we would like to spli…

[LeetCode]36. Valid Sudoku 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/valid-sudoku/description/ 题目描述: Determine if a 9x9 Sudoku board is valid. Only the filled cells need to be validated ac…

[LeetCode]870. Advantage Shuffle 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/advantage-shuffle/description/ 题目描述: Given two arrays A and B of equal size, the advantage of A with respect to B…

[LeetCode]593. Valid Square 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/valid-square/description/ 题目描述: Given the coordinates of four points in 2D space, return whether the four points could…

[LeetCode]435. Non-overlapping Intervals 解题报告(Python) 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/non-overlapping-intervals/description/ 题目描述: Given a collection of intervals, find the minimum number of…

[LeetCode]838. Push Dominoes 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/push-dominoes/description/ 题目描述: There are N dominoes in a line, and we place each domino vertical…

[LeetCode]498. Diagonal Traverse 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/diagonal-traverse/description/ 题目描述: Given a matrix of M x N elements (M rows, N columns), ret…

[LeetCode]481. Magical String 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/magical-string/description/ 题目描述: A magical string S consists of only '1' and '2' and obeys the f…

[LeetCode]397. Integer Replacement 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/integer-replacement/description/ 题目描述: Given a positive integer n and you can do operations as follow: If n is even, replace n with n/2. If n is odd, you…

[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…

[LeetCode]91. Decode Ways 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/decode-ways/description/ 题目描述: A message containing letters from A-Z is being encoded to numbers usin…

[LeetCode]456. 132 Pattern 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/132-pattern/description/ 题目描述: Given a sequence of n integers a1, a2, -, an, a 132 pattern is a subs…

[LeetCode]853. Car Fleet 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 题目地址:https://leetcode.com/problems/car-fleet/description/ 题目描述: N cars are going to the same destination along a one lane road. The desti…

[LeetCode]386. Lexicographical Numbers 解题报告(Python) 标签(空格分隔): LeetCode 作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.me/ 题目地址:https://leetcode.com/problems/lexicographical-numbers/description/ 题目描述: Given an integer n, return 1 - n in lexicogra…

[LeetCode]390. Elimination Game 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/elimination-game/description/ 题目描述: There is a list of sorted integers from 1 to n. Starting from left to right, remove the first number and every other numb…

[LeetCode]647. Palindromic Substrings 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/palindromic-substrings/description/ 题目描述: Given a string, your task is to count how many palindromic substrings in this string. The substrings with dif…

[LeetCode]392. Is Subsequence 解题报告(Python) 标签: LeetCode 题目地址:https://leetcode.com/problems/is-subsequence/description/ 题目描述: Given a string s and a string t, check if s is subsequence of t. You may assume that there is only lower case English letters…