1762. Buildings With an Ocean View

单调栈

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.

Constraints:

• 1 <= heights.length <= 105

• 1 <= heights[i] <= 109

分析

单调栈

class Solution:
    def findBuildings(self, heights: List[int]) -> List[int]:
        stack = []
        for i,h in enumerate(heights):
            while stack and heights[stack[-1]] <= h:
                stack.pop()
            
            stack.append(i)
        return stack