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

The duplicate number is always present in the given array.

Koushik S L
1y
#include<bits/stdc++.h> int duplicateNumber(int *arr, int size) { map<int,int> m; for(int i=0;i<size;i++) { if(m.find(arr[i])==m.end()) { m[arr[i]] = 1; } else return arr[i]; } }
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