Find indices of stable mountains

Array

86.8% acceptance

Feb 25, 2026

104

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.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn stable_mountains(height: Vec<i32>, threshold: i32) -> Vec<i32> {
    (1..height.len())
      .filter(|&i| height[i - 1] > threshold)
      .map(|i| i as i32)
      .collect()
  }
}