Rearrange an array in order - smallest, largest, 2nd smallest, 2nd largest, ..
Last Updated :
21 Aug, 2022
Given an array of integers, the task is to print the array in the order - smallest number, the Largest number, 2nd smallest number, 2nd largest number, 3rd smallest number, 3rd largest number, and so on.....
Examples:
Input : arr[] = [5, 8, 1, 4, 2, 9, 3, 7, 6]
Output :arr[] = {1, 9, 2, 8, 3, 7, 4, 6, 5}
Input : arr[] = [1, 2, 3, 4]
Output :arr[] = {1, 4, 2, 3}
A simple solution is to first find the smallest element and swap it with the first element. Then find the largest element, swap it with the second element, and so on. The time complexity of this solution is O(n2).
An efficient solution is to use sorting.
- Sort the elements of the array.
- Take two variables say i and j and point them to the first and last index of the array respectively.
- Now run a loop and store the elements in the array one by one by incrementing i and decrementing j.
Let's take an array with input 5, 8, 1, 4, 2, 9, 3, 7, 6 and sort them so the array becomes 1, 2, 3, 4, 5, 6, 7, 8, 9. Now take two variables to say i and j and point them to the first and last index of the array respectively, run a loop, and store the value into a new array by incrementing I and decrementing j.get that the final result as 1 9 2 8 3 7 4 6 5.
The flowchart is as follows:
flowchart- rearrangearray
Implementation:
C++
// C++ program to print the array in given order
#include <bits/stdc++.h>
using namespace std;
// Function which arrange the array.
void rearrangeArray(int arr[], int n)
{
// Sorting the array elements
sort(arr, arr + n);
int tempArr[n]; // To store modified array
// Adding numbers from sorted array to
// new array accordingly
int ArrIndex = 0;
// Traverse from begin and end simultaneously
for (int i = 0, j = n - 1; i <= n / 2 || j > n / 2;
i++, j--) {
tempArr[ArrIndex] = arr[i];
ArrIndex++;
tempArr[ArrIndex] = arr[j];
ArrIndex++;
}
// Modifying original array
for (int i = 0; i < n; i++)
arr[i] = tempArr[i];
}
// Driver Code
int main()
{
int arr[] = { 5, 8, 1, 4, 2, 9, 3, 7, 6 };
int n = sizeof(arr) / sizeof(arr[0]);
rearrangeArray(arr, n);
for (int i = 0; i < n; i++)
cout << arr[i] << " ";
return 0;
}
// Java program to print the array in given order
import java.util.Arrays;
public class GFG {
// Function which arrange the array.
static void rearrangeArray(int arr[], int n)
{
// Sorting the array elements
Arrays.sort(arr);
int[] tempArr = new int[n]; // To store modified array
// Adding numbers from sorted array to
// new array accordingly
int ArrIndex = 0;
// Traverse from begin and end simultaneously
for (int i = 0, j = n-1; i <= n / 2 || j > n / 2;
i++, j--) {
if(ArrIndex < n)
{
tempArr[ArrIndex] = arr[i];
ArrIndex++;
}
if(ArrIndex < n)
{
tempArr[ArrIndex] = arr[j];
ArrIndex++;
}
}
// Modifying original array
for (int i = 0; i < n; i++)
arr[i] = tempArr[i];
}
// Driver Code
public static void main(String args[])
{
int arr[] = { 5, 8, 1, 4, 2, 9, 3, 7, 6 };
int n = arr.length;
rearrangeArray(arr, n);
for (int i = 0; i < n; i++)
System.out.print(arr[i]+" ");
}
}
// This code is contributed by Sumit Ghosh
# Python 3 program to print
# the array in given order
# Function which arrange the
# array.
def rearrangeArray(arr, n) :
# Sorting the array elements
arr.sort()
# To store modified array
tempArr = [0] * (n + 1)
# Adding numbers from sorted
# array to new array accordingly
ArrIndex = 0
# Traverse from begin and end
# simultaneously
i = 0
j = n-1
while(i <= n // 2 or j > n // 2 ) :
tempArr[ArrIndex] = arr[i]
ArrIndex = ArrIndex + 1
tempArr[ArrIndex] = arr[j]
ArrIndex = ArrIndex + 1
i = i + 1
j = j - 1
# Modifying original array
for i in range(0, n) :
arr[i] = tempArr[i]
# Driver Code
arr = [ 5, 8, 1, 4, 2, 9, 3, 7, 6 ]
n = len(arr)
rearrangeArray(arr, n)
for i in range(0, n) :
print( arr[i], end = " ")
# This code is contributed by Nikita Tiwari.
// C# program to print the
// array in given order
using System;
public class GFG {
// Function which arrange the array.
static void rearrangeArray(int []arr, int n)
{
// Sorting the array elements
Array.Sort(arr);
// To store modified array
int []tempArr = new int[n];
// Adding numbers from sorted array
// to new array accordingly
int ArrIndex = 0;
// Traverse from begin and end simultaneously
for (int i = 0, j = n-1; i <= n / 2
|| j > n / 2; i++, j--) {
if(ArrIndex < n)
{
tempArr[ArrIndex] = arr[i];
ArrIndex++;
}
if(ArrIndex < n)
{
tempArr[ArrIndex] = arr[j];
ArrIndex++;
}
}
// Modifying original array
for (int i = 0; i < n; i++)
arr[i] = tempArr[i];
}
// Driver Code
public static void Main(String []args)
{
int []arr = {5, 8, 1, 4, 2, 9, 3, 7, 6};
int n = arr.Length;
rearrangeArray(arr, n);
for (int i = 0; i < n; i++)
Console.Write(arr[i] + " ");
}
}
// This code is contributed by Nitin Mittal.
<?php
// PHP program to print
// the array in given order
// Function which
// arrange the array.
function rearrangeArray($arr, $n)
{
// Sorting the
// array elements
sort($arr);
// To store modified array
$tempArr = array($n);
// Adding numbers from
// sorted array to new
// array accordingly
$ArrIndex = 0;
// Traverse from begin
// and end simultaneously
for ($i = 0, $j = $n - 1;
$i <= $n / 2 || $j > $n / 2;
$i++, $j--)
{
$tempArr[$ArrIndex] = $arr[$i];
$ArrIndex++;
$tempArr[$ArrIndex] = $arr[$j];
$ArrIndex++;
}
// Modifying original array
for ($i = 0; $i < $n; $i++)
$arr[$i] = $tempArr[$i];
for ($i = 0; $i < $n; $i++)
echo $arr[$i] . " ";
}
// Driver Code
$arr = array(5, 8, 1, 4, 2,
9, 3, 7, 6 );
$n = count($arr) ;
rearrangeArray($arr, $n);
// This code is contributed
// by Sam007
?>
<script>
// Javascript program to print the
// array in given order
// Function which arrange the array.
function rearrangeArray(arr, n)
{
// Sorting the array elements
arr.sort();
// To store modified array
let tempArr = new Array(n);
// Adding numbers from sorted array
// to new array accordingly
let ArrIndex = 0;
// Traverse from begin and end simultaneously
for (let i = 0, j = n-1; i <= n / 2
|| j > n / 2; i++, j--) {
if(ArrIndex < n)
{
tempArr[ArrIndex] = arr[i];
ArrIndex++;
}
if(ArrIndex < n)
{
tempArr[ArrIndex] = arr[j];
ArrIndex++;
}
}
// Modifying original array
for (let i = 0; i < n; i++)
arr[i] = tempArr[i];
}
// Driver Code
let arr =[5, 8, 1, 4, 2, 9, 3, 7, 6]
let n = arr.length;
rearrangeArray(arr, n);
for (let i = 0; i < n; i++)
document.write(arr[i] + " ");
</script>
Time Complexity: O(n log n),
Auxiliary Space: O(n), since n extra space has been taken.
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