Program for array rotation - GeeksforGeeks

09 Nov, 2021
Write a function rotate(ar[], d, n) that rotates arr[] of size n by d elements.  
Rotation of the above array by 2 will make array 
 
METHOD 1 (Using temp array) 
Input arr[] = [1, 2, 3, 4, 5, 6, 7], d = 2, n =7
1) Store the first d elements in a temp array
   temp[] = [1, 2]
2) Shift rest of the arr[]
   arr[] = [3, 4, 5, 6, 7, 6, 7]
3) Store back the d elements
   arr[] = [3, 4, 5, 6, 7, 1, 2]
Time complexity : O(n) Auxiliary Space : O(d)
METHOD 2 (Rotate one by one)  
leftRotate(arr[], d, n)
start
  For i = 0 to i < d
    Left rotate all elements of arr[] by one
end
To rotate by one, store arr[0] in a temporary variable temp, move arr[1] to arr[0], arr[2] to arr[1] ...and finally temp to arr[n-1]Let us take the same example arr[] = [1, 2, 3, 4, 5, 6, 7], d = 2 Rotate arr[] by one 2 times We get [2, 3, 4, 5, 6, 7, 1] after first rotation and [ 3, 4, 5, 6, 7, 1, 2] after second rotation.Below is the implementation of the above approach :  
C++
C
Java
Python3
C#
PHP
Javascript
// C++ program to rotate an array by// d elements#include <bits/stdc++.h>using namespace std; /*Function to left Rotate arr[] of  size n by 1*/void leftRotatebyOne(int arr[], int n){    int temp = arr[0], i;    for (i = 0; i < n - 1; i++)        arr[i] = arr[i + 1];     arr[n-1] = temp;} /*Function to left rotate arr[] of size n by d*/void leftRotate(int arr[], int d, int n){    for (int i = 0; i < d; i++)        leftRotatebyOne(arr, n);} /* utility function to print an array */void printArray(int arr[], int n){    for (int i = 0; i < n; i++)        cout << arr[i] << " ";} /* Driver program to test above functions */int main(){    int arr[] = { 1, 2, 3, 4, 5, 6, 7 };    int n = sizeof(arr) / sizeof(arr[0]);     // Function calling    leftRotate(arr, 2, n);    printArray(arr, n);     return 0;}
// C program to rotate an array by// d elements#include <stdio.h> /* Function to left Rotate arr[] of size n by 1*/void leftRotatebyOne(int arr[], int n); /*Function to left rotate arr[] of size n by d*/void leftRotate(int arr[], int d, int n){    int i;    for (i = 0; i < d; i++)        leftRotatebyOne(arr, n);} void leftRotatebyOne(int arr[], int n){    int temp = arr[0], i;    for (i = 0; i < n - 1; i++)        arr[i] = arr[i + 1];    arr[n-1] = temp;} /* utility function to print an array */void printArray(int arr[], int n){    int i;    for (i = 0; i < n; i++)        printf("%d ", arr[i]);} /* Driver program to test above functions */int main(){    int arr[] = { 1, 2, 3, 4, 5, 6, 7 };    leftRotate(arr, 2, 7);    printArray(arr, 7);    return 0;}
// Java program to rotate an array by// d elements class RotateArray {    /*Function to left rotate arr[] of size n by d*/    void leftRotate(int arr[], int d, int n)    {        for (int i = 0; i < d; i++)            leftRotatebyOne(arr, n);    }     void leftRotatebyOne(int arr[], int n)    {        int i, temp;        temp = arr[0];        for (i = 0; i < n - 1; i++)            arr[i] = arr[i + 1];        arr[n-1] = temp;    }     /* utility function to print an array */    void printArray(int arr[], int n)    {        for (int i = 0; i < n; i++)            System.out.print(arr[i] + " ");    }     // Driver program to test above functions    public static void main(String[] args)    {        RotateArray rotate = new RotateArray();        int arr[] = { 1, 2, 3, 4, 5, 6, 7 };        rotate.leftRotate(arr, 2, 7);        rotate.printArray(arr, 7);    }} // This code has been contributed by Mayank Jaiswal
# Python3 program to rotate an array by# d elements# Function to left rotate arr[] of size n by d*/def leftRotate(arr, d, n):    for i in range(d):        leftRotatebyOne(arr, n) # Function to left Rotate arr[] of size n by 1*/def leftRotatebyOne(arr, n):    temp = arr[0]    for i in range(n-1):        arr[i] = arr[i + 1]    arr[n-1] = temp          # utility function to print an array */def printArray(arr, size):    for i in range(size):        print ("% d"% arr[i], end =" ")   # Driver program to test above functions */arr = [1, 2, 3, 4, 5, 6, 7]leftRotate(arr, 2, 7)printArray(arr, 7) # This code is contributed by Shreyanshi Arun
// C# program for array rotationusing System; class GFG {    /* Function to left rotate arr[]    of size n by d*/    static void leftRotate(int[] arr, int d,                           int n)    {        for (int i = 0; i < d; i++)            leftRotatebyOne(arr, n);    }     static void leftRotatebyOne(int[] arr, int n)    {        int i, temp = arr[0];        for (i = 0; i < n - 1; i++)            arr[i] = arr[i + 1];         arr[n-1] = temp;    }     /* utility function to print an array */    static void printArray(int[] arr, int size)    {        for (int i = 0; i < size; i++)            Console.Write(arr[i] + " ");    }     // Driver code    public static void Main()    {        int[] arr = { 1, 2, 3, 4, 5, 6, 7 };        leftRotate(arr, 2, 7);        printArray(arr, 7);    }} // This code is contributed by Sam007
<?php// PHP program to rotate an array// by d elements /*Function to left Rotate arr[] of size n by 1*/function leftRotatebyOne(&$arr, $n){    $temp = $arr[0];    for ($i = 0; $i < $n - 1; $i++)        $arr[$i] = $arr[$i + 1];     $arr[$n-1] = $temp;} /*Function to left rotate arr[]  of size n by d*/function leftRotate(&$arr, $d, $n){    for ($i = 0; $i < $d; $i++)        leftRotatebyOne($arr, $n);} /* utility function to print   an array */function printArray(&$arr, $n){    for ($i = 0; $i < $n; $i++)        echo $arr[$i] . " ";} // Driver Code$arr = array( 1, 2, 3, 4, 5, 6, 7 );$n = sizeof($arr); // Function callingleftRotate($arr, 2, $n);printArray($arr, $n); // This code is contributed// by ChitraNayal?>
<script> // JavaScript program to rotate an array by// d elements      /* Function to left rotate arr of size n by d */    function leftRotate(arr , d , n) {        for (i = 0; i < d; i++)            leftRotatebyOne(arr, n);    }     function leftRotatebyOne(arr , n) {        var i, temp;        temp = arr[0];        for (i = 0; i < n - 1; i++)            arr[i] = arr[i + 1];        arr[n - 1] = temp;    }     /* utility function to print an array */    function printArray(arr , n) {        for (i = 0; i < n; i++)            document.write(arr[i] + " ");    }     // Driver program to test above functions             var arr = [ 1, 2, 3, 4, 5, 6, 7 ];        leftRotate(arr, 2, 7);        printArray(arr, 7); // This code is contributed by todaysgaurav </script>
Output :  
3 4 5 6 7 1 2 
Time complexity : O(n * d) Auxiliary Space : O(1)METHOD 3 (A Juggling Algorithm) This is an extension of method 2. Instead of moving one by one, divide the array in different sets where number of sets is equal to GCD of n and d and move the elements within sets. If GCD is 1 as is for the above example array (n = 7 and d =2), then elements will be moved within one set only, we just start with temp = arr[0] and keep moving arr[I+d] to arr[I] and finally store temp at the right place.Here is an example for n =12 and d = 3. GCD is 3 and  
Let arr[] be {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}

a) Elements are first moved in first set – (See below 
   diagram for this movement)
          arr[] after this step --> {4 2 3 7 5 6 10 8 9 1 11 12}

b)    Then in second set.
          arr[] after this step --> {4 5 3 7 8 6 10 11 9 1 2 12}

c)    Finally in third set.
          arr[] after this step --> {4 5 6 7 8 9 10 11 12 1 2 3}
Below is the implementation of the above approach : 
C++
C
Java
Python3
C#
Javascript
// C++ program to rotate an array by// d elements#include <bits/stdc++.h>using namespace std; /*Function to get gcd of a and b*/int gcd(int a, int b){    if (b == 0)        return a;     else        return gcd(b, a % b);} /*Function to left rotate arr[] of siz n by d*/void leftRotate(int arr[], int d, int n){    /* To handle if d >= n */    d = d % n;    int g_c_d = gcd(d, n);    for (int i = 0; i < g_c_d; i++) {        /* move i-th values of blocks */        int temp = arr[i];        int j = i;         while (1) {            int k = j + d;            if (k >= n)                k = k - n;             if (k == i)                break;             arr[j] = arr[k];            j = k;        }        arr[j] = temp;    }} // Function to print an arrayvoid printArray(int arr[], int size){    for (int i = 0; i < size; i++)        cout << arr[i] << " ";} /* Driver program to test above functions */int main(){    int arr[] = { 1, 2, 3, 4, 5, 6, 7 };    int n = sizeof(arr) / sizeof(arr[0]);     // Function calling    leftRotate(arr, 2, n);    printArray(arr, n);     return 0;}
// C program to rotate an array by// d elements#include <stdio.h> /* function to print an array */void printArray(int arr[], int size); /*Function to get gcd of a and b*/int gcd(int a, int b); /*Function to left rotate arr[] of siz n by d*/void leftRotate(int arr[], int d, int n){    int i, j, k, temp;    /* To handle if d >= n */    d = d % n;    int g_c_d = gcd(d, n);    for (i = 0; i < g_c_d; i++) {        /* move i-th values of blocks */        temp = arr[i];        j = i;        while (1) {            k = j + d;            if (k >= n)                k = k - n;            if (k == i)                break;            arr[j] = arr[k];            j = k;        }        arr[j] = temp;    }} /*UTILITY FUNCTIONS*//* function to print an array */void printArray(int arr[], int n){    int i;    for (i = 0; i < n; i++)        printf("%d ", arr[i]);} /*Function to get gcd of a and b*/int gcd(int a, int b){    if (b == 0)        return a;    else        return gcd(b, a % b);} /* Driver program to test above functions */int main(){    int arr[] = { 1, 2, 3, 4, 5, 6, 7 };    leftRotate(arr, 2, 7);    printArray(arr, 7);    getchar();    return 0;}
// Java program to rotate an array by// d elementsclass RotateArray {    /*Function to left rotate arr[] of siz n by d*/    void leftRotate(int arr[], int d, int n)    {        /* To handle if d >= n */        d = d % n;        int i, j, k, temp;        int g_c_d = gcd(d, n);        for (i = 0; i < g_c_d; i++) {            /* move i-th values of blocks */            temp = arr[i];            j = i;            while (true) {                k = j + d;                if (k >= n)                    k = k - n;                if (k == i)                    break;                arr[j] = arr[k];                j = k;            }            arr[j] = temp;        }    }     /*UTILITY FUNCTIONS*/     /* function to print an array */    void printArray(int arr[], int size)    {        int i;        for (i = 0; i < size; i++)            System.out.print(arr[i] + " ");    }     /*Function to get gcd of a and b*/    int gcd(int a, int b)    {        if (b == 0)            return a;        else            return gcd(b, a % b);    }     // Driver program to test above functions    public static void main(String[] args)    {        RotateArray rotate = new RotateArray();        int arr[] = { 1, 2, 3, 4, 5, 6, 7 };        rotate.leftRotate(arr, 2, 7);        rotate.printArray(arr, 7);    }} // This code has been contributed by Mayank Jaiswal
# Python3 program to rotate an array by# d elements# Function to left rotate arr[] of size n by ddef leftRotate(arr, d, n):    d = d % n    g_c_d = gcd(d, n)    for i in range(g_c_d):                 # move i-th values of blocks        temp = arr[i]        j = i        while 1:            k = j + d            if k >= n:                k = k - n            if k == i:                break            arr[j] = arr[k]            j = k        arr[j] = temp # UTILITY FUNCTIONS# function to print an arraydef printArray(arr, size):    for i in range(size):        print ("% d" % arr[i], end =" ") # Function to get gcd of a and bdef gcd(a, b):    if b == 0:        return a;    else:        return gcd(b, a % b) # Driver program to test above functionsarr = [1, 2, 3, 4, 5, 6, 7]n = len(arr)d = 2leftRotate(arr, d, n)printArray(arr, n) # This code is contributed by Shreyanshi Arun
// C# program for array rotationusing System; class GFG {    /* Function to left rotate arr[]    of size n by d*/    static void leftRotate(int[] arr, int d,                           int n)    {        int i, j, k, temp;        /* To handle if d >= n */        d = d % n;        int g_c_d = gcd(d, n);        for (i = 0; i < g_c_d; i++) {            /* move i-th values of blocks */            temp = arr[i];            j = i;            while (true) {                k = j + d;                if (k >= n)                    k = k - n;                if (k == i)                    break;                arr[j] = arr[k];                j = k;            }            arr[j] = temp;        }    }     /*UTILITY FUNCTIONS*/    /* Function to print an array */    static void printArray(int[] arr, int size)    {        for (int i = 0; i < size; i++)            Console.Write(arr[i] + " ");    }     /* Function to get gcd of a and b*/    static int gcd(int a, int b)    {        if (b == 0)            return a;        else            return gcd(b, a % b);    }     // Driver code    public static void Main()    {        int[] arr = { 1, 2, 3, 4, 5, 6, 7 };        leftRotate(arr, 2, 7);        printArray(arr, 7);    }} // This code is contributed by Sam007
<script> // JavaScript program to rotate an array by// d elements /*Function to get gcd of a and b*/function gcd( a, b){    if (b == 0)        return a;    else        return gcd(b, a % b);} /*Function to left rotate arr[] of siz n by d*/function leftRotate(arr, d, n){    /* To handle if d >= n */    d = d % n;    let g_c_d = gcd(d, n);    for (let i = 0; i < g_c_d; i++) {        /* move i-th values of blocks */        let temp = arr[i];        let j = i;         while (1) {            let k = j + d;            if (k >= n)                k = k - n;             if (k == i)                break;             arr[j] = arr[k];            j = k;        }        arr[j] = temp;    }} // Function to print an arrayfunction printArray(arr, size){    for (let i = 0; i < size; i++)        document.write(arr[i] +" ");} /* Driver program to test above functions */let arr = [ 1, 2, 3, 4, 5, 6, 7 ];let n = arr.length;// Function callingleftRotate(arr, 2, n);printArray(arr, n); </script>
Output : 
3 4 5 6 7 1 2 
Time complexity : O(n) Auxiliary Space : O(1) 
Please see following posts for other methods of array rotation: Block swap algorithm for array rotation Reversal algorithm for array rotationPlease write comments if you find any bug in above programs/algorithms. 
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