C++ Exercises: Sort a given unsorted array of integers, in wave form

Last update on August 16 2025 12:56:01 (UTC/GMT +8 hours)

9. Wave Form Sorting of an Array

Write a C++ program to sort a given unsorted array of integers, in wave form.
Note: An array is in wave form when array[0] >= array[1] <= array[2] >= array[3] <= array[4] >= . . . .

Sample Solution:

C++ Code :

#include<iostream> // Header file for input/output stream
#include<algorithm> // Header file for using algorithms like sort
using namespace std; // Using the standard namespace

void swap_elements(int *a, int *b)
{
    int t = *a; // Temporary variable to store the value at pointer a
    *a = *b; // Assigning the value at pointer b to pointer a
    *b = t; // Assigning the value in the temporary variable to pointer b
}

void array_wave(int nums[], int n)
{
    sort(nums, nums+n); // Sorting the array in ascending order using the sort function

    // Loop to create the wave pattern in the array
    for (int i = 0; i < n - 1; i += 2)
        swap_elements(&nums[i], &nums[i+1]); // Swapping adjacent elements to create the wave pattern
}

int main()
{
    int nums[] = {4, 5, 9, 12, 9, 22, 45, 7}; // Declaration and initialization of an integer array
    int n = sizeof(nums) / sizeof(nums[0]); // Calculating the number of elements in the array
    cout << "Original array: ";
    for (int i = 0; i < n; i++)
        cout << nums[i] << " "; // Outputting each element of the array
    array_wave(nums, n); // Calling the function to create a wave pattern in the array
    cout << "\nWave form of the said array: ";
    for (int i = 0; i < n; i++)
       cout << nums[i] << " "; // Outputting each element of the modified array in a wave pattern
    return 0;
}

Sample Output:

Original array: 4 5 9 12 9 22 45 7 
Wave form of the said array: 5 4 9 7 12 9 45 22

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to sort an array in wave form by first sorting the array and then swapping adjacent pairs.
Write a C++ program that rearranges an unsorted array into a wave pattern by iterating with a for loop and swapping elements.
Write a C++ program to transform an array into a wave form without using extra space by modifying it in place.
Write a C++ program that reads an array and outputs it in wave form using a single pass approach after sorting.

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