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Sort even and odd placed elements in increasing order
  • Last Updated : 21 Oct, 2019
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Given a list N, the task is to sort all the elements at odd and even positions in increasing order. After sorting, we need to put all odd positioned elements together, then all even positioned elements

Examples:

Input : [3, 2, 7, 6, 8]
Output : 3 7 8 2 6
Explanation: 
Odd position elements in sorted order are 3, 7, 8.
Even position elements in sorted order are 2, 6.

Input : 1 0 2 7 0 0
Output : 0 1 2 0 0 7
Odd {1, 2, 0}
Even {0, 7, 0}

Approach:

  • Initialize two lists to store the odd and even indexed digits.
  • Traverse through all the digits and store the odd indexed digits at odd_indexes list and the even indexed digits at even_indexes list.
  • Print the elements in the odd_indexes list in sorted order.
  • Print the elements in the even_indexes list in the sorted order.

Below is the implementation:

C++




// C++ implementation of above approach 
#include<bits/stdc++.h>
using namespace std;
  
// function to prin the odd and even indexed digits
void odd_even(int arr[], int n)
{
      
    // lists to store the odd and
    // even positioned digits
    vector<int> odd_indexes;
    vector<int>even_indexes;
      
    // traverse through all the indexes 
    // in the integer
    for (int i = 0; i < n;i++)
    {
  
        // if the digit is in odd_index position
        // append it to odd_position list
        if (i % 2 == 0)
        odd_indexes.push_back(arr[i]);
          
        // else append it to the even_position list
        else
        even_indexes.push_back(arr[i]);
  
    }
          
    // print the elements in the list in sorted order
    sort(odd_indexes.begin(), odd_indexes.end());
    sort(even_indexes.begin(), even_indexes.end());
      
    for(int i = 0; i < odd_indexes.size();i++)
        cout << odd_indexes[i] << " ";
  
    for(int i = 0; i < even_indexes.size(); i++)
        cout << even_indexes[i] << " "
      
  
// Driver code
int main()
{
    int arr[] = {3, 2, 7, 6, 8};
    int n = sizeof(arr)/sizeof(arr[0]);
    odd_even(arr, n);
}
  
// This code is contributed by
// Surendra_Gangwar

Java




// Java implementation of the approach
import java.util.*;
  
class GFG 
{
  
// function to prin the odd and even indexed digits
static void odd_even(int arr[], int n)
{
      
    // lists to store the odd and
    // even positioned digits
    Vector<Integer> odd_indexes = new Vector<Integer>();
    Vector<Integer> even_indexes = new Vector<Integer>();
      
    // traverse through all the indexes 
    // in the integer
    for (int i = 0; i < n;i++)
    {
  
        // if the digit is in odd_index position
        // append it to odd_position list
        if (i % 2 == 0)
            odd_indexes.add(arr[i]);
          
        // else append it to the even_position list
        else
            even_indexes.add(arr[i]);
  
    }
          
    // print the elements in the list in sorted order
    Collections.sort(odd_indexes);
    Collections.sort(even_indexes);
      
    for(int i = 0; i < odd_indexes.size(); i++)
        System.out.print(odd_indexes.get(i) + " ");
  
    for(int i = 0; i < even_indexes.size(); i++)
        System.out.print(even_indexes.get(i) + " "); 
      
  
// Driver code
public static void main(String[] args)
{
    int arr[] = {3, 2, 7, 6, 8};
    int n = arr.length;
    odd_even(arr, n);
}
}
  
// This code is contributed by Rajput-Ji

Python3




# function to prin the odd and even indexed digits
def odd_even(n):
      
    # lists to store the odd and
    # even positioned digits
    odd_indexes = []
    even_indexes = []
      
    # traverse through all the indexes 
    # in the integer
    for i in range(len(n)):
          
        # if the digit is in odd_index position
        # append it to odd_position list
        if i % 2 == 0: odd_indexes.append(n[i])
          
        # else append it to the even_position list
        else: even_indexes.append(n[i])
          
    # print the elements in the list in sorted order
    for i in sorted(odd_indexes): print(i, end =" ")
    for i in sorted(even_indexes): print(i, end =" ")
  
  
# Driver Code
n = [3, 2, 7, 6, 8]
odd_even(n)

C#




// C# implementation of the approach
using System;
using System.Collections.Generic;
  
class GFG 
{
  
// function to prin the odd and even indexed digits
static void odd_even(int []arr, int n)
{
      
    // lists to store the odd and
    // even positioned digits
    List<int> odd_indexes = new List<int>();
    List<int> even_indexes = new List<int>();
      
    // traverse through all the indexes 
    // in the integer
    for (int i = 0; i < n;i++)
    {
  
        // if the digit is in odd_index position
        // append it to odd_position list
        if (i % 2 == 0)
            odd_indexes.Add(arr[i]);
          
        // else append it to the even_position list
        else
            even_indexes.Add(arr[i]);
  
    }
          
    // print the elements in the list in sorted order
    odd_indexes.Sort();
    even_indexes.Sort();
      
    for(int i = 0; i < odd_indexes.Count; i++)
        Console.Write(odd_indexes[i] + " ");
  
    for(int i = 0; i < even_indexes.Count; i++)
        Console.Write(even_indexes[i] + " "); 
      
  
// Driver code
public static void Main(String[] args)
{
    int []arr = {3, 2, 7, 6, 8};
    int n = arr.Length;
    odd_even(arr, n);
}
}
  
// This code is contributed by PrinciRaj1992

PHP




<?php
// PHP implementation of above approach 
  
// function to prin the odd and even 
// indexed digits 
function odd_even($n)
{
      
    // lists to store the odd and
    // even positioned digits 
    $odd_indexes = array();
    $even_indexes = array();
      
    // traverse through all the indexes 
    // in the integer 
    for ($i = 0; $i < sizeof($n); $i++)
    {
          
        // if the digit is in odd_index position 
        // append it to odd_position list 
        if ($i % 2 == 0)
            array_push($odd_indexes, $n[$i]);
          
        // else append it to the even_position list 
        else
            array_push($even_indexes, $n[$i]); 
          
    }
      
    // print the elements in the list in sorted order 
    sort($odd_indexes);
    for ($i = 0; $i < sizeof($odd_indexes); $i++)
        echo $odd_indexes[$i], " ";
          
    sort($even_indexes) ;
    for ($i = 0; $i < sizeof($even_indexes); $i++)
        echo $even_indexes[$i], " ";
}
  
// Driver Code 
$n = array(3, 2, 7, 6, 8);
odd_even($n);
  
// This code is contributed by Ryuga
?>
Output:
3 7 8 2 6

Time Complexity : O(nlogn)

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