Related Articles

# Sort a Bitonic Array

• Last Updated : 13 Aug, 2021

Given a bitonic array arr[] the task is to sort the given bitonic array.

A Bitonic Sequence is a sequence of numbers that is first strictly increasing then after a point strictly decreasing.

Examples:

Input: arr[] = {5, 10, 15, 25, 20, 3, 2, 1}
Output: 1 2 3 5 10 15 20 25
Input: arr[] = {5, 20, 30, 40, 36, 33, 25, 15, 10}
Output: 5 10 15 20 25 30 33 36 40

Approach:

• The idea is to initialize a variable K to the highest power of 2 in size of the array such as to compare elements that are K distant apart.
• Swap the elements if they are not in increasing order.
• Reduce K by half and repeat the process until K becomes zero.

Below is the implementation of the above approach:

## C++

 `// C++ program for the above approach``#include ``using` `namespace` `std;` `// Function to Sort a Bitonic array``// in constant space``void` `sortArr(``int` `a[], ``int` `n)``{``    ``int` `i, k;` `    ``// Initialize the value of k``    ``k = (``int``)log2(n);``    ``k = ``pow``(2, k);` `    ``// In each iteration compare elements``    ``// k distance apart and swap if``    ``// they are not in order``    ``while` `(k > 0) {``        ``for` `(i = 0; i + k < n; i++)``            ``if` `(a[i] > a[i + k])``                ``swap(a[i], a[i + k]);` `        ``// k is reduced to half``        ``// after every iteration``        ``k = k / 2;``    ``}` `    ``// Print the array elements``    ``for` `(i = 0; i < n; i++) {``        ``cout << a[i] << ``" "``;``    ``}``}` `// Driver Code``int` `main()``{``    ``// Given array arr[]``    ``int` `arr[] = { 5, 20, 30, 40, 36, 33, 25, 15, 10 };``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);` `    ``// Function Call``    ``sortArr(arr, n);` `    ``return` `0;``}`

## Java

 `// Java program for the above approach``import` `java.io.*;` `class` `GFG{``    ` `// Function to Sort a Bitonic array``// in constant space``static` `void` `sortArr(``int` `a[], ``int` `n)``{``    ``int` `i, k;` `    ``// Initialize the value of k``    ``k = (``int``)(Math.log(n) / Math.log(``2``));``    ``k = (``int``) Math.pow(``2``, k);` `    ``// In each iteration compare elements``    ``// k distance apart and swap if``    ``// they are not in order``    ``while` `(k > ``0``)``    ``{``        ``for``(i = ``0``; i + k < n; i++)``            ``if` `(a[i] > a[i + k])``            ``{``                ``int` `tmp = a[i];``                ``a[i] = a[i + k];``                ``a[i + k] = tmp;``            ``}` `        ``// k is reduced to half``        ``// after every iteration``        ``k = k / ``2``;``    ``}` `    ``// Print the array elements``    ``for``(i = ``0``; i < n; i++)``    ``{``        ``System.out.print(a[i] + ``" "``);``    ``}``}``    ` `// Driver code``public` `static` `void` `main (String[] args)``{``    ` `    ``// Given array arr[]``    ``int` `arr[] = { ``5``, ``20``, ``30``, ``40``, ``36``,``                  ``33``, ``25``, ``15``, ``10` `};``    ``int` `n = arr.length;``    ` `    ``// Function call``    ``sortArr(arr, n);``}``}` `// This code is contributed by offbeat`

## Python3

 `# Python3 program for the``# above approach``import` `math` `# Function to sort bitonic``# array in constant space``def` `sortArr(a, n):` `    ``# Initialize thevalue of k``    ``k ``=` `int``(math.log(n, ``2``))``    ``k ``=` `int``(``pow``(``2``, k))` `    ``# In each iteration compare elements``    ``# k distance apart and swap it``    ``# they are not in order``    ``while``(k > ``0``):``        ``i ``=` `0``        ``while` `i ``+` `k < n:``            ``if` `a[i] > a[i ``+` `k]:``                ``a[i], a[i ``+` `k] ``=` `a[i ``+` `k], a[i]``            ``i ``=` `i ``+` `1``            ` `        ``# k is reduced to half after``        ``# every iteration``        ``k ``=` `k ``/``/` `2``    ` `    ``# Print the array elements    ``    ``for` `i ``in` `range``(n):``        ``print``(a[i], end ``=` `" "``)` `# Driver code` `# Given array``a ``=` `[ ``5``, ``20``, ``30``, ``40``, ``36``, ``33``, ``25``, ``15``, ``10` `]``n ``=` `len``(a)` `# Function call``sortArr(a, n)` `# This code is contributed by virusbuddah_`

## C#

 `// C# program for the above approach``using` `System;` `class` `GFG{``    ` `// Function to Sort a Bitonic array``// in constant space``static` `void` `sortArr(``int` `[]a, ``int` `n)``{``    ``int` `i, k;` `    ``// Initialize the value of k``    ``k = (``int``)(Math.Log(n) / Math.Log(2));``    ``k = (``int``) Math.Pow(2, k);` `    ``// In each iteration compare elements``    ``// k distance apart and swap if``    ``// they are not in order``    ``while` `(k > 0)``    ``{``        ``for``(i = 0; i + k < n; i++)``            ``if` `(a[i] > a[i + k])``            ``{``                ``int` `tmp = a[i];``                ``a[i] = a[i + k];``                ``a[i + k] = tmp;``            ``}` `        ``// k is reduced to half``        ``// after every iteration``        ``k = k / 2;``    ``}` `    ``// Print the array elements``    ``for``(i = 0; i < n; i++)``    ``{``        ``Console.Write(a[i] + ``" "``);``    ``}``}``    ` `// Driver code``public` `static` `void` `Main(String[] args)``{``    ` `    ``// Given array []arr``    ``int` `[]arr = { 5, 20, 30, 40, 36,``                  ``33, 25, 15, 10 };``    ``int` `n = arr.Length;``    ` `    ``// Function call``    ``sortArr(arr, n);``}``}` `// This code is contributed by amal kumar choubey`

## Javascript

 ``
Output:
`5 10 15 20 25 30 33 36 40`

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

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with experts, please refer DSA Live Classes for Working Professionals and Competitive Programming Live for Students.

My Personal Notes arrow_drop_up