Problem Description
There are n mountains in a row, and each mountain has a height. You are given an integer array height where height[i] represents the height of mountain i, and an integer threshold. A mountain is called stable if the mountain just before it (if it exists) has a height strictly greater than threshold. Note that mountain 0 is not stable. Return an array containing the indices of all stable mountains in any order.
Key Insights
- A mountain is stable if its previous mountain's height is greater than the given threshold.
- The first mountain (index 0) cannot be stable by definition.
- Iterate through the array starting from index 1 to check for stable conditions.
Space and Time Complexity
Time Complexity: O(n)
Space Complexity: O(k), where k is the number of stable mountains found.
Solution
To find the indices of stable mountains, we can use a simple loop to iterate through the heights array starting from the second mountain (index 1). For each mountain, we check if the height of the previous mountain is greater than the threshold. If so, we record the index of the current mountain as stable. We use a list to store the indices of stable mountains and return it at the end.