链接:https://ac.nowcoder.com/acm/contest/884/K来源:牛客网 题目描述 300iq loves numbers who are multiple of 300. One day he got a string consisted of numbers. He wants to know how many substrings in the string are multiples of 300 when considered as decimal inte…

>传送门< 题意:给你一个字符串s,求出其中能整除300的子串个数(子串要求是连续的,允许前面有0) 思路: >动态规划 记f[i][j]为右端点满足mod 300 = j的子串个数,可以容易的转移 则状态转移方程为:f[i][(10*j+num[i]) %300] = f[i][(10*j+num[i]) %300] + f[i-1][j] 解释:假如给你个数3,很容易得出3mod300的值就是3,f[3] = 1,然后在3后面加一位1,变为31,则31mod300的值为31,f[31…

https://ac.nowcoder.com/acm/contest/884/K 一开始整了好几个假算法,还好测了一下自己的样例过了. 考虑到300的倍数都是3的倍数+至少两个零(或者单独的0). 求以第i个位置的数为结尾的前缀和为j的数的方案数. 当遇到至少两个0的时候,ans+=dp[0][i-2]+1. +1是那两个0的贡献. 这样子算会漏算单独的0的贡献,最后加回去. 还因为忘记mod3段错误好几次. 老了. #include <bits/stdc++.h> using namesp…

number 题意 给一个数字串,问有几个子串是300的倍数 分析 dp写法:这题一看就很dp,直接一个状态dp[i][j]在第i位的时候膜300的余数是j左过去即可.这题比赛的时候样例老是少1,后面发现是中间忘记加上了,铁憨憨,以后一定要冷静,分析状态,找到少的那部分. #include<bits/stdc++.h> #include<vector> #include<algorithm> using namespace std; #define pb push_ba…

题目传送门 题意: 输入一个只包含数字的字符串,求出是300的倍数的子串的个数(不同位置的0.00.000等都算,并考虑前导零的情况). sample input: 600 123000321013200987000789 sample output: 4 55 题解: O(n)做法:遍历一遍,求前缀和sum取余3,统计sum的个数num[sum],遇到本位和下一位都是0,则把之前统计的个数加上,最后加上单独0的个数. O(300n)DP做法:如下 官方题解: Code: O(n)做法如下: /…

示例1: 输入:600 输出:4 说明:'600', '0', '0', '00' are multiples of 300. (Note that '0' are counted twice because it appeared two times) 示例2: 输入:123000321013200987000789 输出:55 题意:给一个全由数字字符组成的字符串,求出是300倍数的子串的个数.0,00,000等都算,并考虑前导为0的情况. 题解:让求的是300的倍数,但是呢我们可以拆成既是…

Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements.    Your algorithm's time complexity must be…

Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. public class Solution { //桶排序 public List<In…

Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's time complexity must be bet…

Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: 347. Top K Frequent ElementsYou may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's…

Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's time complexity must be bet…

题目:输入n个整数,找出其中最小的k个数,例如输入4,5,1,6,2,7,3,8 这8个数字,则最小的四个数字为1,2,3,4, 这道题是典型的TopK问题,剑指Offer提供了两种方法来实现,一种方法是parition方法,一种 方法是建立一个大小为k的堆进行topk求解 这里我们只解释第一种方法: 1.首先随机查找数组中一个元素作为一个基准,然后parition一次使得数组左边的元素小于基本,数组右边的元素大于基准. 2.此时将再将基准插入到数组适当的位置并返回该位置的索引. 3.如果索引i…

Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first. Example 1: Inpu…

Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first. Example 1: Inpu…

Given a non-empty array of integers, return the k most frequent elements. Example 1: Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2] Example 2: Input: nums = [1], k = 1 Output: [1] Note: You may assume k is always valid, 1 ≤ k ≤ number of unique ele…

Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first. Example 1: Inpu…

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 347. Top K Frequent Elements - 题解 在线提交: https://leetcode.com/problems/top-k-frequent-elements/ Description Given a non-empty array of integers…

［抄题］: Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's time complexity must…

230. 二叉搜索树中第K小的元素 题意 给定一个二叉搜索树,编写一个函数 kthSmallest 来查找其中第 k 个最小的元素. 你可以假设 k 总是有效的,1 ≤ k ≤ 二叉搜索树元素个数. 解题思路 中序遍历,利用Python3中提供的生成器方法: 中序遍历,判断存储结点值的数组是否到到k,则表明访问的一个结点就是第k个最小的元素: 先获取跟结点处于的位置(第几个最小的元素),如果它比k小,则从右子结点中找,如果它比k大,则从左子节点中找: 实现 class Solution:    …

Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first. Example 1: Inpu…

Given a non-empty array of integers, return the k most frequent elements. Example 1: Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2] Example 2: Input: nums = [1], k = 1 Output: [1] Note: You may assume k is always valid, 1 ≤ k ≤ number of unique ele…

Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's time complexity must be bet…

https://leetcode.com/problems/top-k-frequent-words/ Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the l…

k邻近算法的伪代码: 对未知类别属性的数据集中的每个点一次执行以下操作: (1)计算已知类别数据集中的点与当前点之间的距离: (2)按照距离递增次序排列 (3)选取与当前点距离最小的k个点 (4)确定前k个点所在类别的出现频率 (5)返回前k个点出现频率最好的类别作为当前点的预测分类 python函数实现 ''' Created on Sep 16, 2010 kNN: k Nearest Neighbors Input: inX: vector to compare to existing d…

一.概述 k-近邻算法采用测量不同特征值之间的距离方法进行分类. 工作原理:首先有一个样本数据集合(训练样本集),并且样本数据集合中每条数据都存在标签(分类),即我们知道样本数据中每一条数据与所属分类的对应关系,输入没有标签的数据之后,将新数据的每个特征与样本集的数据对应的特征进行比较(欧式距离运算),然后算出新数据与样本集中特征最相似(最近邻)的数据的分类标签,一般我们选择样本数据集中前k个最相似的数据,然后再从k个数据集中选出出现分类最多的分类作为新数据的分类. 二.优缺点 优点:精度高.对…

''' Created on Nov 06, 2017 kNN: k Nearest Neighbors Input: inX: vector to compare to existing dataset (1xN) dataSet: size m data set of known vectors (NxM) labels: data set labels (1xM vector) k: number of neighbors to use for comparison (should be…

题目描述: Given a non-empty array of integers, return the k most frequent elements. For example,Given [1,1,1,2,2,3] and k = 2, return [1,2]. Note: You may assume k is always valid, 1 ≤ k ≤ number of unique elements. Your algorithm's time complexity must…

Given a non-empty list of words, return the k most frequent elements. Your answer should be sorted by frequency from highest to lowest. If two words have the same frequency, then the word with the lower alphabetical order comes first. Example 1: Inpu…

Given a non-empty array of integers, return the k most frequent elements. Example 1: Input: nums = [1,1,1,2,2,3], k = 2 Output: [1,2] Example 2: Input: nums = [1], k = 1 Output: [1] Note: You may assume k is always valid, 1 ≤ k ≤ number of unique ele…

k近邻法 模型 使用的模型实际上对应于特征空间的划分.模型的三个基本要素:1.距离度量 2. k值的选择 3. 分类决策规则决定. k值的选择:k值的选择,k如果选择的过小会导致过拟合,模型会变得复杂． 思想脉络 方法的流程简述:给定一个训练数据集,对于新的输入实例,在训练数据集中找到与之最临近的k个实例,这k个实例的多数属于某个类, 就把实例分为这个类.这个算法没有显示的训练过程,应用的过程就是训练的过程 算法推导 1 公式推导无显示的算法推导过程.要注意的是,不同的距离度量所确定的最近邻点是…