Practice/Meta/Leetcode 1762. Buildings With an Ocean View

Leetcode 1762. Buildings With an Ocean View

CodingMust

Problem

You are given an array representing the heights of buildings standing in a row along a coastline. The ocean is located to the right of all buildings. A building has an ocean view if there are no buildings of equal or greater height anywhere to its right.

Return the indices of all buildings that have an ocean view, sorted in ascending order.

Requirements

1. Identify all buildings with an unobstructed view to the ocean on the right side
2. A building has a view if no building to its right has equal or greater height
3. Return indices in ascending order
4. The rightmost building always has an ocean view (nothing blocks it)

Constraints

• 1 ≤ heights.length ≤ 10^5
• 1 ≤ heights[i] ≤ 10^9
• Aim for O(n) time complexity and O(1) extra space (excluding output array)

Examples

Example 1:

` Input: heights = [4, 2, 3, 1] Output: [0, 2, 3] Explanation:

• Building 0 (height 4): No taller building to the right → has view
• Building 1 (height 2): Building at index 2 (height 3) blocks it → no view
• Building 2 (height 3): Only shorter building to right → has view
• Building 3 (height 1): Last building always has view `

Example 2:

Input: heights = [5, 4, 3, 2, 1] Output: [0, 1, 2, 3, 4] Explanation: Heights strictly decrease, so every building is taller than all buildings to its right.

Example 3:

Input: heights = [1, 2, 3, 4, 5] Output: [4] Explanation: Only the last building has a view since each prior building is blocked by a taller one to its right.