class Solution {
    public List<Integer> findBuildingViewCount(int[] heights) {
        int n = heights.length;
        if (n == 1) return Collections.singletonList(0);

        List<Integer> leftView =  new ArrayList<>();
        List<Integer> rightView =  new ArrayList<>();

        int left = 0, right = n - 1;
        leftView.add(left);
        rightView.add(right);

        while (left < right) {
            if (heights[left] < heights[right]) {
                if (heights[left] > heights[leftView.get(leftView.size()-1)]) {
                    leftView.add(left);
                }
                left++;
            } else {
                if (heights[right] > heights[rightView.get(rightView.size()-1)]) {
                    rightView.add(right);
                }
                right--;
            }
        }

        // Merge rightView in correct order (from rightmost to leftmost)
        while (!rightView.isEmpty()) {
            leftView.add(rightView.remove(rightView.size()-1));
        }

        return new ArrayList<>(leftView);
    }
}