1762. Buildings With an Ocean View

There are n buildings in a line. You are given an integer array heights of size n that represents the heights of the buildings in the line.

The ocean is to the right of the buildings. A building has an ocean view if the building can see the ocean without obstructions. Formally, a building has an ocean view if all the buildings to its right have a smaller height.

Return a list of indices (0-indexed) of buildings that have an ocean view, sorted in increasing order.

Example 1:

复制代码

Input: heights = [4,2,3,1]
Output: [0,2,3]
Explanation: Building 1 (0-indexed) does not have an ocean view because building 2 is taller.

Example 2:

复制代码

Input: heights = [4,3,2,1]
Output: [0,1,2,3]
Explanation: All the buildings have an ocean view.

Example 3:

复制代码

Input: heights = [1,3,2,4]
Output: [3]
Explanation: Only building 3 has an ocean view.

Constraints:

1 <= heights.length <= 105
1 <= heights[i] <= 109

java 复制代码

public class Solution {
    public int[] findBuildings(int[] heights) {
        ArrayList<Integer> results = new ArrayList<Integer>();

        if (heights == null || heights.length == 0) {
            return new int[0]; // Return an empty array if input is null or empty
        }

        int highest_building = -1;

        for (int i = heights.length - 1; i >= 0; i--) {
            if (heights[i] > highest_building) {
                highest_building = heights[i];
                results.add(i); // 从右往左遍历，把最高的楼房存下来
            }
        }

        // Convert the ArrayList<Integer> to int[] 这里要特别注意，Interger的arraylist到int的array要手动转换一下。
        int[] resultArray = new int[results.size()];
        int j = 0;
        for (int i = results.size() - 1; i >=0; i--) {
            resultArray[j] = results.get(i);
            j++;
        }

        return resultArray;
    }
}