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
endTo 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++ 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
// 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
// Java program to rotate an array by// d elementsclass 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
# 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#
// 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// 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?> |
Javascript
<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++ program to rotate an array by// d elements#include <bits/stdc++.h>using namespace std;/*Fuction 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
// C program to rotate an array by// d elements#include <stdio.h>/* function to print an array */void printArray(int arr[], int size);/*Fuction 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]);}/*Fuction 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
// 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] + " "); } /*Fuction 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
# 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 =" ")# Fuction 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#
// 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] + " "); } /* Fuction 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 |
Javascript
<script>// JavaScript program to rotate an array by// d elements/*Fuction 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 rotation
Please write comments if you find any bug in above programs/algorithms.
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