1762. Buildings With an Ocean View

https://leetcode.com/problems/buildings-with-an-ocean-view

Description

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:

**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:

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

Example 3:

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

Example 4:

**Input:** heights = [2,2,2,2]
**Output:** [3]
**Explanation:** Buildings cannot see the ocean if there are buildings of the **same** height to its right.

Constraints:

• 1 <= heights.length <= 105

• 1 <= heights[i] <= 109

ac

class Solution {
    public int[] findBuildings(int[] heights) {
        // Edge cases
        if (heights == null) {
            return null;
        }
        
        Stack<Integer> stack = new Stack<>();
        int max = 0;
        for (int i = heights.length - 1; i >= 0; i--) {
            if (heights[i] > max) {
                stack.push(i);
                max = heights[i];
            }
        }
        
        int[] res = new int[stack.size()];
        for (int i = 0; i < res.length; i++) {
            res[i] = stack.pop();
        }
        
        return res;
    }
}