# Can array list have duplicate values?

## Can array list have duplicate values?

Duplicates : ArrayList allows duplicate values while HashSet doesn’t allow duplicates values. Ordering : ArrayList maintains the order of the object in which they are inserted while HashSet is an unordered collection and doesn’t maintain any order.

## How do you find duplicate values in an array in C++?

1. using namespace std;
2. int findDuplicate(vector &nums) {
3. int duplicate = -1;
4. for (int i = 0; i < nums. size(); i++) {
5. int val = abs(nums[i]);
6. nums[val-1] = -nums[val-1]; }
7. duplicate = val; break;
8. for (int i = 0; i < nums. size(); i++) {

How do you check if a number is repeated in an array?

function checkIfArrayIsUnique(myArray) { for (var i = 0; i < myArray. length; i++) { for (var j = 0; j < myArray. length; j++) { if (i != j) { if (myArray[i] == myArray[j]) { return true; // means there are duplicate values } } } } return false; // means there are no duplicate values. }

How do you duplicate rows in numbers?

To copy a row, click the row number to highlight the row and then use the keyboard shortcut; or, click the drop-down arrow next to the rows number and select Copy.

### How do you find duplicates in an array?

One of the most common ways to find duplicates is by using the brute force method, which compares each element of the array to every other element. This solution has the time complexity of O(n^2) and only exists for academic purposes.

### How do I check if an array has duplicates?

Can we add duplicate values in list?

As we know List(ArrayList, Vector, and LinkedList) allow duplicate element. Let’s see a couple of ways to avoid duplicate elements in List.

How do you count the number of repeated values in an array?

call by int[] repeat=NumberMath. NumberofRepeat(array) for find repeat count. Each location contains how many repeat corresponding value of array…

#### How do you find duplicate values in an array Java?

The standard way to find duplicate elements from an array is by using the HashSet data structure. If you remember, Set abstract data type doesn’t allow duplicates. You can take advantage of this property to filter duplicate elements.

#### How to find duplicates in an array of integers?

Given an array of n + 1 integers between 1 and n, find one of the duplicates. If there are multiple possible answers, return one of the duplicates. If there is no duplicate, return -1. Example: Input: [1, 2, 2, 3]

How to find repeating numbers in an array?

Given an array of n elements containing elements from 0 to n-1, with any of these numbers appearing any number of times, find these repeating numbers in O (n) and using only constant memory space. Input: n = 7 , array = {1, 2, 3, 1, 3, 6, 6} Output: 1, 3 and 6.

Which is the best way to find a duplicate number?

Optimal Approach for Find The Duplicate Number 1 Method 1 (Hashing) 2 Method 2 (XOR) 3 Method 3 (Cycle Detection)

## How to find duplicate element in linked list?

The duplicate element is (X ^ Y). The above problem can be solved by the cycle finding algorithm in Linked List using two pointers slow and fast, the slow pointer moves by one step and fast move by two steps in every iteration. Initialize two pointers slow and fast as nums [0].