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 }