1762. Buildings with an Ocean View

We can calculate buildings with an ocean view by iterating from the front and then keeping a monotonic stack — if we see a building that’s larger than previous buildings, we pop all smaller buildings we’ve seen so far.

At the end we return the buildings that still are in the stack.

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