Find the Duplicate Number Problem Statement

Given an integer array 'ARR' of size 'N' containing numbers from 0 to (N - 2). Each number appears at least once, and there is one number that appears twice. Your task is to find and return this duplicate number.

Example:

Input:

t = 1
N = 5
ARR = [0, 3, 1, 2, 3]

Output:

3

Explanation:

The number '3' is the duplicate because it appears twice in the array.

Constraints:

1

Question

Find the Duplicate Number Problem Statement

Given an integer array 'ARR' of size 'N' containing numbers from 0 to (N - 2). Each number appears at least once, and there is one number that appears twice. Your task is to find and return this duplicate number.

Example:

Input:

t = 1
N = 5
ARR = [0, 3, 1, 2, 3]

Output:

Explanation:

The number '3' is the duplicate because it appears twice in the array.

Constraints:

1 <= t <= 10^2
0 <= N <= 10^3
Time Limit: 1 sec

Note:

The duplicate number is always present in the given array.

Accepted Answer

Given an array of size N containing numbers from 0 to (N-2), find and return the duplicate number.

Iterate through the array and keep track of the frequency of each number using a hashmap.
Return the number with a frequency of 2.

Accepted Answer

List not allowed duplicate values

Accepted Answer

First find xor of all the element between 1 to n in o(1) using n%4 trick and then xor the result with all the elements of array linearly. PS: if you don't know the n%4 trick... here it is https://www.geeksforgeeks.org/calculate-xor-1-n/amp/

Accepted Answer

Duplicate values are not allowed

Accepted Answer

List not allowed duplicate values

Asked in TCS