Check if all array elements are distinct - GeeksforGeeks

16 Jun, 2021
Given an array, check whether all elements in an array are distinct or not.Examples:  
Input : 1, 3, 2, 4
Output : Yes

Input : "Geeks", "for", "Geeks"
Output : No

Input : "All", "Not", "Equal"
Output : Yes
 
One simple solution is to use two nested loops. For every element, check if it repeats or not. If any element repeats, return false. If no element repeats, return false.An efficient solution is to Hashing. We put all array elements in a HashSet. If size of HashSet remains same as array size, then we return true. 
C++
Java
Python3
C#
Javascript
// C++ program to check if all array// elements are distinct#include <bits/stdc++.h>using namespace std; bool areDistinct(vector<int> arr){    int n = arr.size();     // Put all array elements in a map    unordered_set<int> s;    for (int i = 0; i < n; i++) {        s.insert(arr[i]);    }     // If all elements are distinct, size of    // set should be same array.    return (s.size() == arr.size());} // Driver codeint main(){    std::vector<int> arr = { 1, 2, 3, 2 };     if (areDistinct(arr)) {        cout << "All Elements are Distinct";    }    else {        cout << "Not all Elements are Distinct";    }     return 0;}
// Java program to check if all array elements are// distinct or not.import java.util.Arrays;import java.util.HashSet;import java.util.Set; public class DistinctElements {    public static boolean areDistinct(Integer arr[])    {        // Put all array elements in a HashSet        Set<Integer> s =           new HashSet<Integer>(Arrays.asList(arr));         // If all elements are distinct, size of        // HashSet should be same array.        return (s.size() == arr.length);    }     // Driver code    public static void main(String[] args)    {        Integer[] arr = { 1, 2, 3, 2 };        if (areDistinct(arr))            System.out.println("All Elements are Distinct");        else            System.out.println("Not all Elements are Distinct");    }}
# Python3 program to check if all array# elements are distinctdef areDistinct(arr) :     n = len(arr)     # Put all array elements in a map    s = set()    for i in range(0, n):        s.add(arr[i])         # If all elements are distinct,    # size of set should be same array.    return (len(s) == len(arr)) # Driver codearr = [ 1, 2, 3, 2 ] if (areDistinct(arr)):    print("All Elements are Distinct") else :    print("Not all Elements are Distinct") # This code is contributed by ihritik
// C# program to check if all array elements are// distinct or not.using System;using System.Collections.Generic; public class DistinctElements{    public static bool areDistinct(int []arr)    {        // Put all array elements in a HashSet        HashSet<int> s = new HashSet<int>(arr);         // If all elements are distinct, size of        // HashSet should be same array.        return (s.Count == arr.Length);    }     // Driver code    public static void Main(String[] args)    {        int[] arr = { 1, 2, 3, 2 };        if (areDistinct(arr))            Console.WriteLine("All Elements are Distinct");        else            Console.WriteLine("Not all Elements are Distinct");    }} // This code has been contributed by 29AjayKumar
<script>// Javascript program to check if all array// elements are distinctfunction areDistinct(arr){    let n = arr.length;     // Put all array elements in a map    let s = new Set();    for (let i = 0; i < n; i++) {        s.add(arr[i]);    }     // If all elements are distinct, size of    // set should be same array.    return (s.size == arr.length);} // Driver code    let arr = [ 1, 2, 3, 2 ];     if (areDistinct(arr)) {        document.write("All Elements are Distinct");    }    else {        document.write("Not all Elements are Distinct");    } // This code is contributed// by _saurabh_jaiswal</script>
Not all Elements are Distinct
 
Subhashni Singh
29AjayKumar
ihritik
_saurabh_jaiswal
java-hashset
Arrays
Hash
Java Programs
Arrays
Hash
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
Comments
Old Comments
Trapping Rain Water
Program to find sum of elements in a given array
Reversal algorithm for array rotation
Window Sliding Technique
Find duplicates in O(n) time and O(1) extra space | Set 1
Internal Working of HashMap in Java
Hashing | Set 1 (Introduction)
Hashing | Set 3 (Open Addressing)
Count pairs with given sum
Hashing | Set 2 (Separate Chaining)