LeetCode[1762] Buildings With an Ocean View

1762. Buildings With an Ocean View

Medium

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

 

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class Solution { public int[] findBuildings(int[] heights) { List<Integer> list = new ArrayList<>(); int n = heights.length; int tall = 0; for(int i = n-1; i>=0; --i){ if(heights[i]>tall){ list.add(0, i); tall = Math.max(tall, heights[i]); } } int[] ret = new int[list.size()]; for(int i=0; i<list.size(); ++i) ret[i] = list.get(i); return ret; } }