701204. Rotate and delete
Rotate and Delete
Summary
The "Rotate and Delete" problem is a medium-level algorithmic challenge that involves rotating an array and deleting certain elements. The goal is to rotate the array by a specified number of positions, then delete all occurrences of a target element from the resulting array.
Key concepts involved in this problem include arrays, data structures, and algorithms for rotation and deletion.
Detailed Explanation
To solve this problem, we can follow these steps:
- Initialize an empty result array to store the rotated elements.
- Calculate the number of positions to rotate the array by considering the direction (clockwise or counterclockwise) and the target element's position.
- Perform the rotation operation on the original array based on the calculated offset.
- Iterate through the rotated array, deleting all occurrences of the target element.
The time complexity for this solution is O(n), where n is the size of the input array. This is because we need to iterate through the entire array twice: once for rotation and once for deletion.
Space complexity is O(1) as we are not using any additional space that scales with the input size.
Here's a step-by-step breakdown of the solution:
- Calculate the offset for rotation based on the direction (clockwise or counterclockwise).
- Rotate the array by shifting elements to the left or right based on the calculated offset.
- Iterate through the rotated array, deleting all occurrences of the target element.
Here's an ASCII art diagram illustrating the rotation and deletion process:
Original Array: [1, 2, 3, 4, 5]
Rotate
Rotated Array: [3, 4, 5, 1, 2] (rotated counterclockwise)
Delete Target Element (2)
Final Result: [3, 4, 5]
Optimized Solutions
Java
public int[] rotateAndDelete(int[] arr, int target) {
int n = arr.length;
int offset = getRotationOffset(arr, target);
int[] result = new int[n];
System.arraycopy(arr, offset, result, 0, n - offset);
for (int i = 0; i < n; i++) {
if (result[i] != target) {
result[i] = arr[(i + offset) % n];
}
}
return result;
}
private int getRotationOffset(int[] arr, int target) {
for (int i = 0; i < arr.length; i++) {
if (arr[i] == target) {
return i;
}
}
return 0;
}