Print all Distinct (Unique) Elements in given Array (original) (raw)

Last Updated : 02 Nov, 2024

Given an integer array **arr[], print all **distinct elements from this array. The given array may contain **duplicates and the output should contain every element only once.

**Examples:

**Input: arr[] = {12, 10, 9, 45, 2, 10, 10, 45}
****Output: {**12, 10, 9, 45, 2}

**Input: arr[] = {1, 2, 3, 4, 5}
**Output: {1, 2, 3, 4, 5}

**Input: arr[] = {1, 1, 1, 1, 1}
****Output: {**1}

Table of Content

[Naive Approach] Using Nested loops – O(n^2) Time and O(1) Space
[Better Approach] Using Sorting – O(n * log n) Time and O(1) Space
[Expected Approach] Using Hashing – O(n) Time and O(n) Space

**[Naive Approach] Using Nested loops – O(n^2) Time and O(1) Space

The idea is to use **two nested loops. The outer loop picks an element one by one starting from the leftmost element. The inner loop checks if the element is present on left side of it. If present, then ignore the element, else store it in result.

C++ `

// C++ program to print all distinct elements in an // array using nested loops

#include #include using namespace std;

vector findDistinct(vector &arr) { vector res;

for (int i = 0; i < arr.size(); i++) {

    // Check if this element is included in result
    int j;
    for (j = 0; j < i; j++)
        if (arr[i] == arr[j])
            break;

    // Include this element if not included previously
    if (i == j)
        res.push_back(arr[i]);
}
return res;

}

int main() { vector arr = {12, 10, 9, 45, 2, 10, 10, 45}; vector res = findDistinct(arr);

for (int ele : res)
    cout << ele << " ";
return 0;

}

C

// C program to print all distinct elements in an // array using nested loops

#include <stdio.h>

int* findDistinct(int *arr, int size, int *resSize) { int res = (int)malloc(size * sizeof(int)); *resSize = 0;

for (int i = 0; i < size; i++) {
    // Check if this element is included in result
    int j;
    for (j = 0; j < i; j++)
        if (arr[i] == arr[j])
            break;

    // Include this element if not included previously
    if (i == j)
        res[(*resSize)++] = arr[i];
}
return res;

}

int main() { int arr[] = {12, 10, 9, 45, 2, 10, 10, 45}; int size = sizeof(arr) / sizeof(arr[0]); int resSize;

int *res = findDistinct(arr, size, &resSize);

for (int i = 0; i < resSize; i++)
    printf("%d ", res[i]);

free(res);
return 0;

}

Java

// JAva program to print all distinct elements in an // array using nested loops

import java.util.*;

class GfG { static ArrayList findDistinct(int[] arr) { ArrayList res = new ArrayList<>();

    for (int i = 0; i < arr.length; i++) {

        // Check if this element is included in result
        int j;
        for (j = 0; j < i; j++)
            if (arr[i] == arr[j])
                break;

        // Include this element if not included previously
        if (i == j)
            res.add(arr[i]);
    }
    return res;
}

public static void main(String[] args) {
    int[] arr = {12, 10, 9, 45, 2, 10, 10, 45};
  
    ArrayList<Integer> res = findDistinct(arr);
    for (int val : res) {
        System.out.print(val + " ");
    }
}

}

Python

Python program to print all distinct elements in an

array using nested loops

def findDistinct(arr): res = []

for i in range(len(arr)):

    # Check if this element is included in result
    j = 0
    while j < i:
        if arr[i] == arr[j]:
            break
        j += 1

    # Include this element if not included previously
    if i == j:
        res.append(arr[i])

return res

if name == "main": arr = [12, 10, 9, 45, 2, 10, 10, 45] res = findDistinct(arr) for val in res: print(val, end=" ")

C#

// C# program to print all distinct elements in an // array using nested loops

using System; using System.Collections.Generic;

class GfG { static List findDistinct(int[] arr) { List res = new List(); for (int i = 0; i < arr.Length; i++) {

        // Check if this element is included in result
        int j;
        for (j = 0; j < i; j++)
            if (arr[i] == arr[j])
                break;

        // Include this element if not included previously
        if (i == j)
            res.Add(arr[i]);
    }
    return res;
}

static void Main() {
    int[] arr = {12, 10, 9, 45, 2, 10, 10, 45};
  
    List<int> res = findDistinct(arr);
    foreach (int val in res) {
        Console.Write(val + " ");
    }
}

}

JavaScript

// JavaScript program to print all distinct elements in an // array using nested loops

function findDistinct(arr) { let res = [];

for (let i = 0; i < arr.length; i++) {

    // Check if this element is included in result
    let j;
    for (j = 0; j < i; j++)
        if (arr[i] === arr[j])
            break;

    // Include this element if not included previously
    if (i === j)
        res.push(arr[i]);
}

return res;

}

let arr = [12, 10, 9, 45, 2, 10, 10, 45]; let res = findDistinct(arr); console.log(res.join(" "));

[Better Approach] Using Sorting **– O(n*logn) Time and O(1) Space**

The idea is to **sort the array so that all occurrences of every element become **consecutive. Once the occurrences become **consecutive, we can traverse the sorted array and print **distinct elements by ignoring elements if they are same as the previous element.

C++ `

// C++ program to print all distinct elements in an // array using sorting

#include #include #include

using namespace std;

vector findDistinct(vector &arr) { vector res; int n = arr.size();

// First sort the array so that all occurrences 
// become consecutive
sort(arr.begin(), arr.end());

for (int i = 0; i < n; i++) {
  
   // Store elements only if they are different 
   // from previous element
   if(i == 0 || arr[i] != arr[i - 1]) {
       res.push_back(arr[i]);
   }
}
  return res;

}

int main() { vector arr = {12, 10, 9, 45, 2, 10, 10, 45};

vector<int> res = findDistinct(arr);
  for(int ele: res) {
      cout << ele << " ";
}
return 0;

}

C

// C program to print all distinct elements in an // array using sorting

#include <stdio.h>

int compare(const void *a, const void b) { return ((int *)a - *(int *)b); }

void findDistinct(int *arr, int n, int **res, int *resSize) { // First sort the array so that all occurrences // become consecutive qsort(arr, n, sizeof(int), compare);

*res = (int *)malloc(n * sizeof(int));
int index = 0;

for (int i = 0; i < n; i++) {
    // Store elements only if they are different 
    // from previous element
    if (i == 0 || arr[i] != arr[i - 1]) {
        (*res)[index++] = arr[i];
    }
}
*resSize = index;

}

int main() { int arr[] = {12, 10, 9, 45, 2, 10, 10, 45}; int n = sizeof(arr) / sizeof(arr[0]);

int *res;
int resSize;

findDistinct(arr, n, &res, &resSize);
for (int i = 0; i < resSize; i++) {
    printf("%d ", res[i]);
}
return 0;

}

Java

// Java program to print all distinct elements in an // array using sorting

import java.util.Arrays; import java.util.ArrayList;

class GfG { static ArrayList findDistinct(int[] arr) { ArrayList res = new ArrayList<>(); int n = arr.length;

    // First sort the array so that all occurrences 
    // become consecutive
    Arrays.sort(arr);

    for (int i = 0; i < n; i++) {
        
        // Store elements only if they are different 
        // from previous element
        if (i == 0 || arr[i] != arr[i - 1]) {
            res.add(arr[i]);
        }
    }
    return res;
}

public static void main(String[] args) {
    int[] arr = {12, 10, 9, 45, 2, 10, 10, 45};

    ArrayList<Integer> res = findDistinct(arr);
    for (int ele : res) {
        System.out.print(ele + " ");
    }
}

}

Python

Python program to print all distinct elements in an

array using sorting

def findDistinct(arr): res = [] n = len(arr)

# First sort the array so that all occurrences 
# become consecutive
arr.sort()

for i in range(n):
    
    # Store elements only if they are different 
    # from previous element
    if i == 0 or arr[i] != arr[i - 1]:
        res.append(arr[i])

return res

if name == "main": arr = [12, 10, 9, 45, 2, 10, 10, 45]

res = findDistinct(arr)
for ele in res:
    print(ele, end=" ")

C#

// C# program to print all distinct elements in an // array using sorting

using System; using System.Collections.Generic;

class GfG { static List findDistinct(List arr) { List res = new List(); int n = arr.Count;

    // First sort the array so that all occurrences 
    // become consecutive
    arr.Sort();

    for (int i = 0; i < n; i++) {
        // Store elements only if they are different 
        // from previous element
        if (i == 0 || arr[i] != arr[i - 1]) {
            res.Add(arr[i]);
        }
    }
    return res;
}

static void Main() {
    List<int> arr = new List<int> { 12, 10, 9, 45, 2, 10, 10, 45 };

    List<int> res = findDistinct(arr);
    foreach (int ele in res) {
        Console.Write(ele + " ");
    }
}

}

JavaScript

// JavaScript program to print all distinct elements in an // array using sorting

function findDistinct(arr) { let res = []; let n = arr.length;

// First sort the array so that all occurrences 
// become consecutive
arr.sort((a, b) => a - b);

for (let i = 0; i < n; i++) {
    
    // Store elements only if they are different 
    // from previous element
    if (i === 0 || arr[i] !== arr[i - 1]) {
        res.push(arr[i]);
    }
}
return res;

}

const arr = [12, 10, 9, 45, 2, 10, 10, 45];

const res = findDistinct(arr); console.log(res.join(" "));

**[Expected Approach] Using Hashing – O(n) Time and O(n) Space

We can u**se **Hashing to store distinct element. The idea is to insert all the elements in a hash set and then traverse the hash set to store the distinct elements in the resultant array.

C++ `

// C++ program to print all distinct elements // of a given array

#include #include #include using namespace std;

// function to return all distinct elements vector findDistinct(vector &arr) {

// Initialize set with all elements of array
unordered_set<int> st (arr.begin(), arr.end());

// Return the result array by inserting all 
// elements from hash set
  return vector<int> (st.begin(), st.end());

}

int main () { vector arr = {12, 10, 9, 45, 2, 10, 10, 45};

  vector<int> res = findDistinct(arr);
  for (int ele: res)
      cout << ele << " ";
return 0;

}

Java

// Java program to print all distinct elements // of a given array

import java.util.HashSet; import java.util.ArrayList;

class GfG {

// function to return all distinct elements
static ArrayList<Integer> findDistinct(int[] arr) {
    
    // Initialize set with all elements of array
    HashSet<Integer> st = new HashSet<>();
    for (int num : arr) {
        st.add(num);
    }
    
    // Return the result array by inserting all 
    // elements from hash set
    return new ArrayList<>(st);
}

public static void main(String[] args) {
    int[] arr = {12, 10, 9, 45, 2, 10, 10, 45};
    
    ArrayList<Integer> res = findDistinct(arr);
    for (int ele : res) {
        System.out.print(ele + " ");
    }
}

}

Python

Python program to print all distinct elements

of a given array

function to return all distinct elements

def findDistinct(arr):

# Initialize set with all elements of array
st = set(arr)

# Return the result array by inserting all 
# elements from hash set
return list(st)

if name == "main": arr = [12, 10, 9, 45, 2, 10, 10, 45]

res = findDistinct(arr)
for ele in res:
    print(ele, end=" ")

C#

// C# program to print all distinct elements // of a given array

using System; using System.Collections.Generic;

class GfG {

// function to return all distinct elements
static List<int> findDistinct(List<int> arr) {
  
    // Initialize set with all elements of array
    HashSet<int> st = new HashSet<int>(arr);

    // Return the result array by inserting all 
    // elements from hash set
    return new List<int>(st);
}

static void Main() {
    List<int> arr = new List<int> { 12, 10, 9, 45, 2, 10, 10, 45 };
    
    List<int> res = findDistinct(arr);
    foreach (int ele in res)
        Console.Write(ele + " ");
}

}

JavaScript

// JavaScript program to print all distinct elements // of a given array

// function to return all distinct elements function findDistinct(arr) {

// Initialize set with all elements of array
const st = new Set(arr);

// Return the result array by inserting all 
// elements from hash set
return Array.from(st);

}

const arr = [12, 10, 9, 45, 2, 10, 10, 45];

const res = findDistinct(arr); console.log(res.join(" "));

Print all Distinct (Unique) Elements in given Array (original) (raw)

**[Naive Approach] Using Nested loops – O(n^2) Time and O(1) Space

Python program to print all distinct elements in an

array using nested loops

**[Better Approach] Using **Sorting – O(n*logn) Time and O(1) Space

Python program to print all distinct elements in an

array using sorting

**[Expected Approach] Using Hashing – O(n) Time and O(n) Space

Python program to print all distinct elements

of a given array

function to return all distinct elements

[Better Approach] Using Sorting **– O(n*logn) Time and O(1) Space**