442. Find All Duplicates in an ArrayMediumTopicsCompaniesGiven an integer array nums of length n where all the integers of nums are in the range [1, n] and each integer appears once or twice, return an array of all the integers that appears twice.You must write an algorithm that runs in O(n) time and uses only constant extra space. Example 1:Input: nums = [4,3,2,7,8,2,3,1]Output: [2,3]Example 2:Input: nums = [1,1,2]Output: [1]Example 3:Input: nums = [1]Output: [] Constraints:n == nums.length1 <= n <= 1051 <= nums[i] <= nEach element in nums appears once or twice.
Question
- Find All Duplicates in an ArrayMediumTopicsCompaniesGiven an integer array nums of length n where all the integers of nums are in the range [1, n] and each integer appears once or twice, return an array of all the integers that appears twice.You must write an algorithm that runs in O(n) time and uses only constant extra space. Example 1:Input: nums = [4,3,2,7,8,2,3,1]Output: [2,3]Example 2:Input: nums = [1,1,2]Output: [1]Example 3:Input: nums = [1]Output: [] Constraints:n == nums.length1 <= n <= 1051 <= nums[i] <= nEach element in nums appears once or twice.
Solution
The problem is asking to find all the duplicate numbers in an array. The array contains numbers in the range from 1 to n and each number appears once or twice. The algorithm should run in O(n) time and use only constant extra space.
Here is a step-by-step solution:
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Initialize an empty list to store the duplicate numbers.
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Iterate over the array. For each number, convert the number at the index equal to the absolute value of the current number minus one to negative.
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If the number at the index equal to the absolute value of the current number minus one is already negative, it means the current number is a duplicate. Add it to the list of duplicates.
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Return the list of duplicates.
Here is a Python solution:
def findDuplicates(nums):
duplicates = []
for num in nums:
if nums[abs(num) - 1] < 0:
duplicates.append(abs(num))
else:
nums[abs(num) - 1] *= -1
return duplicates
This solution works because when we find a number, we mark the number at the index equal to the number minus one as negative. If we find a number and the number at the index equal to the number minus one is already negative, it means we have seen this number before, so it is a duplicate.
Similar Questions
Given an integer array nums of length n where all the integers of nums are in the range [1, n] and each integer appears once or twice, return an array of all the integers that appears twice.You must write an algorithm that runs in O(n) time and uses only constant extra space. Example 1:Input: nums = [4,3,2,7,8,2,3,1]Output: [2,3]Example 2:Input: nums = [1,1,2]Output: [1]Example 3:Input: nums = [1]Output: [] Constraints:
You have a set of integers s, which originally contains all the numbers from 1 to n. Unfortunately, due to some error, one of the numbers in s got duplicated to another number in the set, which results in repetition of one number and loss of another number.You are given an integer array nums representing the data status of this set after the error.Find the number that occurs twice and the number that is missing and return them in the form of an array. Example 1:Input: nums = [1,2,2,4]Output: [2,3]
Problem StatementArun is given an array of integers where all elements appear twice, except for one element that appears only once. The goal is to find this single, non-duplicate element using a linear search algorithm. If the element is not found, print the appropriate message.Assist Arun in solving this challenge.Input format :The first line of input consists of an integer N, representing the number of elements in the array.The second line consists of N space-separated integers, representing the array elements.Output format :The output prints an integer, representing the single non-duplicate element in the given array.If no such element is found, print "No non-duplicate element found".Refer to the sample output for formatting specifications.Code constraints :1 ≤ N ≤ 151 ≤ elements of the array ≤ 30Sample test cases :Input 1 :91 1 2 3 3 4 4 8 8Output 1 :2Input 2 :712 16 12 15 17 16 15Output 2 :17Input 3 :414 26 14 26Output 3 :No non-duplicate element found
Given an array of integers A, 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?Problem Constraints1 <= |A| <= 20000000 <= A[i] <= INTMAXInput FormatFirst and only argument of input contains an integer array A.Output FormatReturn a single integer denoting the single element.Example InputInput 1: A = [1, 2, 2, 3, 1]Input 2: A = [1, 2, 2]Example OutputOutput 1: 3Output 2: 1Example ExplanationExplanation 1:3 occurs once.Explanation 2:1 occurs once.
Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of unique elements in nums.Consider the number of unique elements of nums to be k, to get accepted, you need to do the following things:Change the array nums such that the first k elements of nums contain the unique elements in the order they were present in nums initially. The remaining elements of nums are not important as well as the size of nums.Return k.Custom Judge:The judge will test your solution with the following code:int[] nums = [...]; // Input arrayint[] expectedNums = [...]; // The expected answer with correct lengthint k = removeDuplicates(nums); // Calls your implementationassert k == expectedNums.length;for (int i = 0; i < k; i++) { assert nums[i] == expectedNums[i];}If all assertions pass, then your solution will be accepted. Example 1:Input: nums = [1,1,2]Output: 2, nums = [1,2,_]Explanation: Your function should return k = 2, with the first two elements of nums being 1 and 2 respectively.It does not matter what you leave beyond the returned k (hence they are underscores).Example 2:Input: nums = [0,0,1,1,1,2,2,3,3,4]Output: 5, nums = [0,1,2,3,4,_,_,_,_,_]Explanation: Your function should return k = 5, with the first five elements of nums being 0, 1, 2, 3, and 4 respectively.It does not matter what you leave beyond the returned k (hence they are underscores). Constraints:1 <= nums.length <= 3 * 104-100 <= nums[i] <= 100nums is sorted in non-decreasing order.
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