Is there a method in Ruby that takes an array, and counts all unique elements and their occurrences and passes them back as a hash? For example ['A','A','A','A','B','B','C'].method > {'A' => 4, 'B' => 2, 'C' => 1} Something like that. ['A','A'…

Count the number of occurrences in a sorted array Given a sorted array arr[] and a number x, write a function that counts the occurrences of x in arr[]. Expected time complexity is O(Logn) Examples: Input: arr[] = {1, 1, 2, 2, 2, 2, 3,}, x = 2 Output…

数unique island, 比如 110000 110001 001101 101100 100000 总共两个unique岛,不是四个 方法可以是记录每次新的岛屿搜索的路径,left,right,up,down, 作为标志是否相同的key,存hashset package fbOnsite; import java.util.*; public class UniqueIsland { public int countIsland(int[][] grid) { HashSet<Strin…

,,,,}; //把数组的值赋给vector vector<int> vec(arr, arr+sizeof(arr)/sizeof(int)); 解法一: 时间复杂度O(n) 空间复杂度O(1) class Solution { public: void moveZeroes(vector<int>& nums) { ; //nums中,[0,...k)的元素均为非0元素 //遍历到第i个元素后,保证[0,...i)中所有非0元素 //都按照顺序排列在[0,...k)中…

Let's say we are going to find out number of occurrences of a number in a sorted array using binary search in O(log n) time. For example the given array is: [1,1,3,5,5,5,5,5,9,11], the number 5 appears 5 times; the number 3 appears 1 time; 2 appears…

Find the unique elements of an array. Returns the sorted unique elements of an array. There are three optional outputs in addition to the unique elements: the indices of the input array that give the unique values, the indices of the unique array tha…

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…

Install Ruby(安装) For windows you can download Ruby from http://rubyforge.org/frs/?group_id=167 for Linux tryhttp://www.rpmfind.net. Our first program(从此开始) Enter the following into the file, "test.rb". puts "Howdy!" At the C: prompt en…

Non-unique Elements You are given a non-empty list of integers (X). For this task, you should return a list consisting of only the non-unique elements in this list. To do so you will need to remove all unique elements (elements which are contained in…