Reversal algorithm for array rotation

Reversal algorithm for array rotation

// C program for reversal algorithm of array rotation

#include<stdio.h>

/*Utility function to print an array */

void printArray(int arr[], int size);

/* Utility function to reverse arr[] from start to end */

void rvereseArray(int arr[], int start, int end);

/* Function to left rotate arr[] of size n by d */

void leftRotate(int arr[], int d, int n)

{

    rvereseArray(arr, 0, d-1);

    rvereseArray(arr, d, n-1);

    rvereseArray(arr, 0, n-1);

}

/*UTILITY FUNCTIONS*/

/* function to print an array */

void printArray(int arr[], int size)

{

    int i;

    for (i = 0; i < size; i++)

        printf("%d ", arr[i]);

}

 /*Function to reverse arr[] from index start to end*/

void rvereseArray(int arr[], int start, int end)

{

    int temp;

    while (start < end)

    {

        temp = arr[start];

        arr[start] = arr[end];

        arr[end] = temp;

        start++;

        end--;

    }

}

/* Driver program to test above functions */

int main()

{

    int arr[] = {1, 2, 3, 4, 5, 6, 7};

    int n = sizeof(arr)/sizeof(arr[0]);

    int d = 2;

    leftRotate(arr, d, n);

    printArray(arr, n);

    return 0;

}

Output :

3 4 5 6 7 1 2

Example :

Input :  arr[] = [1, 2, 3, 4, 5, 6, 7]

         d = 2

Output : arr[] = [3, 4, 5, 6, 7, 1, 2]