2.2K
Iterative way:
1) Initialize start and end indexes.
start = 0, end = n-1
2) In a loop, swap arr[start] with arr[end] and change start and end as follows.
start = start +1; end = end – 1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | /* Function to reverse arr[] from start to end*/void rvereseArray(int arr[], int start, int end){ int temp; while(start < end) { temp = arr[start]; arr[start] = arr[end]; arr[end] = temp; start++; end--; }}/* Utility that prints out an array on a line */void printArray(int arr[], int size){ int i; for (i=0; i < size; i++) printf("%d ", arr[i]); printf("\n");}/* Driver function to test above functions */int main(void){ int arr[] = {1, 2, 3, 4, 5, 6}; printArray(arr, 6); rvereseArray(arr, 0, 5); printf("Reversed array is \n"); printArray(arr, 6); return 0;} |
Time Complexity: O(n)
Recursive Way:
1) Initialize start and end indexes
start = 0, end = n-1
2) Swap arr[start] with arr[end]
3) Recursively call reverse for rest of the array.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | /* Function to reverse arr[] from start to end*/void rvereseArray(int arr[], int start, int end){ int temp; if(start >= end) return; temp = arr[start]; arr[start] = arr[end]; arr[end] = temp; rvereseArray(arr, start+1, end-1);}/* Utility that prints out an array on a line */void printArray(int arr[], int size){ int i; for (i=0; i < size; i++) printf("%d ", arr[i]); printf("\n");}/* Driver function to test above functions */int main(){ int arr[] = {1, 2, 3, 4, 5}; printArray(arr, 5); rvereseArray(arr, 0, 4); printf("Reversed array is \n"); printArray(arr, 5); return 0;} |
Time Complexity: O(n)
