Data Structure Array: Program for array rotation

http://www.geeksforgeeks.org/array-rotation/

O(n), O(1)

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <stack>
#include <string>
#include <fstream>
#include <map>
using namespace std;

int gcd(int a, int b) {
    return b == 0? a : gcd(b, a % b);
}

void leftrotate(int arr[], int d, int n) {
    for (int i = 0; i < gcd(d, n); i++) {
        int tmp = arr[i];
        int j = i;
        while (1) {
            int k = j + d;
            if (k >= n) k -= n;
            if (k == i) break;
            arr[j] = arr[k];
            j = k;
        }
        arr[j] = tmp;
    }
}

int main() {
    int arr[7] = {1, 2, 3, 4, 5, 6, 7};
    leftrotate(arr, 2, 7);
    for (int i = 0; i < 7; i++) cout << arr[i] << " ";
    return 0;
}

 O(n), O(1)

#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
#include <stack>
#include <string>
#include <fstream>
#include <map>
using namespace std;

void reverse(int arr[], int a, int b) {
    for (int i = 0; i < (b-a)/2; i++) swap(arr[a+i], arr[b-1-i]);
}

void leftrotate(int arr[], int d, int n) {
    reverse(arr, 0, d);
    reverse(arr, d, n);
    reverse(arr, 0, n);
}

int main() {
    int arr[7] = {1, 2, 3, 4, 5, 6, 7};
    leftrotate(arr, 2, 7);
    for (int i = 0; i < 7; i++) cout << arr[i] << " ";
    return 0;
}