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.

Video Explanation​

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Example 1:​

Input: height = [1,2,3,4,5], threshold = 2

Output: [3,4]

Explanation:

Mountain 3 is stable because height[2] == 3 is greater than threshold == 2. Mountain 4 is stable because height[3] == 4 is greater than threshold == 2.

Example 2:​

Input: height = [10,1,10,1,10], threshold = 3

Output: [1,3]

Example 3:​

Input: height = [10,1,10,1,10], threshold = 10

Output: [ ]

Approach​

1. Iterate Through Mountains: Loop through the array starting from the second mountain.

2. Check Stability: Compare the height of the current mountain with the height of the previous mountain.

3. Collect Stable Indices: If the previous mountain's height is greater than the threshold, add the current mountain's index to the result list.

Code in Java

Solutions​

class Solution {
public:
    vector<int> stableMountains(vector<int>& height, int threshold) {
        vector<int> result;
        for (int i = 1; i < height.size(); i++) {
            if (height[i - 1] > threshold) {
                result.push_back(i);
            }
        }
        return result;
    }
};

class Solution {
    public List<Integer> stableMountains(int[] height, int threshold) {
        List<Integer> stableMountains = new ArrayList<>();
        for(int i=1; i<height.length; i++) {
            if(height[i-1]>threshold) {
                stableMountains.add(i);
            }
        }
        return stableMountains;
    }
}

class Solution:
    def stableMountains(self, height: List[int], threshold: int) -> List[int]:
        return [i for i in range(1, len(height)) if height[i - 1] > threshold]

var stableMountains = function(height, threshold) {
    const result = [];
    for (let i = 1; i < height.length; i++) {
        if (height[i - 1] > threshold) {
            result.push(i);
        }
    }
    return result;
};