Data Structure Array: Program for array rotation

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

O(n), O(1)

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <queue>
 5 #include <stack>
 6 #include <string>
 7 #include <fstream>
 8 #include <map>
 9 using namespace std;
10 
11 int gcd(int a, int b) {
12     return b == 0? a : gcd(b, a % b);
13 }
14 
15 void leftrotate(int arr[], int d, int n) {
16     for (int i = 0; i < gcd(d, n); i++) {
17         int tmp = arr[i];
18         int j = i;
19         while (1) {
20             int k = j + d;
21             if (k >= n) k -= n;
22             if (k == i) break;
23             arr[j] = arr[k];
24             j = k;
25         }
26         arr[j] = tmp;
27     }
28 }
29 
30 int main() {
31     int arr[7] = {1, 2, 3, 4, 5, 6, 7};
32     leftrotate(arr, 2, 7);
33     for (int i = 0; i < 7; i++) cout << arr[i] << " ";
34     return 0;
35 }

O(n), O(1)

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 #include <queue>
 5 #include <stack>
 6 #include <string>
 7 #include <fstream>
 8 #include <map>
 9 using namespace std;
10 
11 void reverse(int arr[], int a, int b) {
12     for (int i = 0; i < (b-a)/2; i++) swap(arr[a+i], arr[b-1-i]);
13 }
14 
15 void leftrotate(int arr[], int d, int n) {
16     reverse(arr, 0, d);
17     reverse(arr, d, n);
18     reverse(arr, 0, n);
19 }
20 
21 int main() {
22     int arr[7] = {1, 2, 3, 4, 5, 6, 7};
23     leftrotate(arr, 2, 7);
24     for (int i = 0; i < 7; i++) cout << arr[i] << " ";
25     return 0;
26 }