Monotonic array

Array

62.2% acceptance

Feb 22, 2026

3265

107

An array is monotonic if it is either monotone increasing or monotone decreasing. An array nums is monotone increasing if for all i <= j, nums[i] <= nums[j]. An array nums is monotone decreasing if for all i <= j, nums[i] >= nums[j]. Given an integer array nums, return true if the given array is monotonic, or false otherwise.

Solution

Rust

Time O(1)

Space O(1)

LeetCode

solution.rs

/*
 * An array is monotonic if it is either monotone increasing or monotone decreasing.
 * An array nums is monotone increasing if for all i <= j, nums[i] <= nums[j]. An array nums is monotone decreasing if for all i <= j, nums[i] >= nums[j].
 * Given an integer array nums, return true if the given array is monotonic, or false otherwise.
 * Example 1:
 * Input: nums = [1,2,2,3]
 * Output: true
 * Example 2:
 * Input: nums = [6,5,4,4]
 * Output: true
 * Example 3:
 * Input: nums = [1,3,2]
 * Output: false
 * Constraints:
 * 1 <= nums.length <= 105
 * -105 <= nums[i] <= 105
 */

impl Solution {
  pub fn is_monotonic(nums: Vec<i32>) -> bool {
    let inc = nums.windows(2).all(|w| w[0] <= w[1]);
    let dec = nums.windows(2).all(|w| w[0] >= w[1]);
    inc || dec
  }
}