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Print all unique elements present in a sorted array

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  • Difficulty Level : Medium
  • Last Updated : 20 Oct, 2021
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Given a sorted array arr[] of size N, the task is to print all the unique elements in the array.

An array element is said to be unique if the frequency of that element in the array is 1.

Examples:

Input: arr[ ] = {1, 1, 2, 2, 3, 4, 5, 5}
Output: 3 4
Explanation: Since 1, 2, 5 are occurring more than once in the array, the distinct elements are 3 and 4.

Input: arr[ ] = {1, 2, 3, 3, 3, 4, 5, 6}
Output: 1 2 4 5 6

Approach: The simplest approach to solve the problem is to traverse the array arr[] and print only those elements whose frequency is 1. Follow the steps below to solve the problem:

  • Iterate over the array arr[] and initialize a variable, say cnt = 0,   to count the frequency of the current array element.
  • Since the array is already sorted, check if the current element is the same as the previous element. If found to be true, then update cnt += 1.
  • Otherwise, if cnt = 1, then print the element. Otherwise, continue.

Below is the implementation of the above approach:

C++




// C++ Program for the above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to print all unique
// elements present in a sorted array
void RemoveDuplicates(int arr[], int n)
{
 
    int i = 0;
 
    // Traverse the array
    while (i < n) {
 
        int cur = arr[i];
 
        // Stores frequency of
        // the current element
        int cnt = 0;
 
        // Iterate until end of the
        // array is reached or current
        // element is not the same as the
        // previous element
        while (i < n and cur == arr[i]) {
            cnt++;
            i++;
        }
 
        // If current element is unique
        if (cnt == 1) {
 
            cout << cur << " ";
        }
    }
}
 
// Driver Code
int main()
{
 
    // Given Input
    int arr[] = { 1, 3, 3, 5, 5, 6, 10 };
    int N = 7;
 
    // Function Call
    RemoveDuplicates(arr, N);
 
    return 0;
}


Java




// Java Program for the above approach
import java.io.*;
 
class GFG
{
   
  // Function to print all unique
  // elements present in a sorted array
  static void RemoveDuplicates(int arr[], int n)
  {
 
    int i = 0;
 
    // Traverse the array
    while (i < n) {
 
      int cur = arr[i];
 
      // Stores frequency of
      // the current element
      int cnt = 0;
 
      // Iterate until end of the
      // array is reached or current
      // element is not the same as the
      // previous element
      while (i < n && cur == arr[i]) {
        cnt++;
        i++;
      }
 
      // If current element is unique
      if (cnt == 1) {
        System.out.print(cur +" ");
      }
    }
  }
 
  // Driver Code
 
  public static void main (String[] args)
  {
 
    // Given Input
    int arr[] = { 1, 3, 3, 5, 5, 6, 10 };
    int N = 7;
 
    // Function Call
    RemoveDuplicates(arr, N);
  }
}
 
// This code is contributed by Potta Lokesh


Python3




# Function to print all unique
# elements present in a sorted array
def RemoveDuplicates(arr, n):
    i = 0
    while i < n:
        cur = arr[i]
         
        # Stores frequency of
        # the current element
        cnt = 0
 
        # Iterate until end of the
        # array is reached or current
        # element is not the same as the
        # previous element
        while i < n and cur == arr[i]:
            cnt += 1
            i += 1
        if cnt == 1:
            print(cur, end=" ")
 
# Driver code
if __name__ == "__main__":
   
    # Given Input
    arr = [1, 3, 3, 5, 5, 6, 10]
    N = 7
 
    # Function Call
    RemoveDuplicates(arr, N)
     
# This code is contributed by Kushagra Bansal


C#




// C# Program for the above approach
using System;
 
class GFG {
 
    // Function to print all unique
    // elements present in a sorted array
    static void RemoveDuplicates(int[] arr, int n)
    {
 
        int i = 0;
 
        // Traverse the array
        while (i < n) {
 
            int cur = arr[i];
 
            // Stores frequency of
            // the current element
            int cnt = 0;
 
            // Iterate until end of the
            // array is reached or current
            // element is not the same as the
            // previous element
            while (i < n && cur == arr[i]) {
                cnt++;
                i++;
            }
 
            // If current element is unique
            if (cnt == 1) {
                Console.Write(cur + " ");
            }
        }
    }
 
    // Driver Code
 
    public static void Main()
    {
 
        // Given Input
        int[] arr = { 1, 3, 3, 5, 5, 6, 10 };
        int N = 7;
 
        // Function Call
        RemoveDuplicates(arr, N);
    }
}
 
// This code is contributed by rishavmahato348.


Javascript




<script>
       // JavaScript Program for the above approach
 
       // Function to print all unique
       // elements present in a sorted array
       function RemoveDuplicates(arr, n) {
 
           let i = 0;
 
           // Traverse the array
           while (i < n) {
 
               let cur = arr[i];
 
               // Stores frequency of
               // the current element
               let cnt = 0;
 
               // Iterate until end of the
               // array is reached or current
               // element is not the same as the
               // previous element
               while (i < n && cur == arr[i]) {
                   cnt++;
                   i++;
               }
 
               // If current element is unique
               if (cnt == 1) {
 
                   document.write(cur + " ");
               }
           }
       }
 
       // Driver Code
 
       // Given Input
       let arr = [1, 3, 3, 5, 5, 6, 10];
       let N = 7;
 
       // Function Call
       RemoveDuplicates(arr, N);
 
   // This code is contributed by Potta Lokesh
 
   </script>


Output

1 6 10 

Time Complexity: O(N)
Auxiliary Space: O(1)


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