C Exercises: Generate a random permutation of array elements

Last update on March 18 2025 13:21:05 (UTC/GMT +8 hours)

77. Random Permutations of Array Elements

Write a program in C to generate random permutations of array elements.

Expected Output:
The given array is:
1 2 3 4 5 6 7 8
The shuffled elements in the array are:
2 8 7 3 4 5 1 6

The task is to write a C program that generates random permutations of the elements in a given array. The program should shuffle the array elements in a random order, ensuring that each permutation is equally likely. The output should display the original array and its shuffled version.

Visual Presentation:

Sample Solution:

C Code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

// Function to swap the values of two integers
void changeValues(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

// Function to display elements of an array
void ArrayDisplay(int arr1[], int n) {
    printf("The shuffled elements in the array are:  \n");
    for (int i = 0; i < n; i++)
        printf("%d ", arr1[i]);
    printf("\n");
}

// Function to shuffle an array randomly
void shuffleRandom(int arr1[], int n) {
    srand(time(NULL)); // Seed for random number generation

    for (int i = n - 1; i > 0; i--) {
        int j = rand() % (i + 1); // Generate a random index between 0 and i
        changeValues(&arr1[i], &arr1[j]); // Swap elements at indices i and j
    }
}

int main() {
    int arr1[] = {1, 2, 3, 4, 5, 6, 7, 8};
    int n = sizeof(arr1) / sizeof(arr1[0]);
    int i;

    // Print the original array
    printf("The given array is:  \n");
    for (i = 0; i < n; i++) {
        printf("%d  ", arr1[i]);
    }
    printf("\n");

    shuffleRandom(arr1, n); // Shuffle the array
    ArrayDisplay(arr1, n); // Display the shuffled array

    return 0;
}

Output:

The given array is: 
1  2  3  4  5  6  7  8  
The shuffled elements in the array are:  
2 8 7 3 4 5 1 6 

Flowchart:/p>

For more Practice: Solve these Related Problems:

• Write a C program to generate random permutations of an array using the Fisher-Yates shuffle algorithm.
• Write a C program to recursively generate all possible permutations of an array.
• Write a C program to generate random permutations and then check for uniqueness of each permutation.
• Write a C program to shuffle an array using pointer arithmetic and random swaps.

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