Number of sub arrays of size k and average greater than or equal to threshold

Array Sliding Window

72.3% acceptance

Feb 25, 2026

1830

111

Given an array of integers arr and two integers k and threshold, return the number of sub-arrays of size k and average greater than or equal to threshold.

Solution

Rust

Time O(n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn num_of_subarrays(arr: Vec<i32>, k: i32, threshold: i32) -> i32 {
    let k = k as usize;
    let min_sum = threshold * k as i32;
    let mut sum: i32 = arr[..k].iter().sum();
    let mut count = if sum >= min_sum { 1 } else { 0 };
    for i in k..arr.len() {
      sum += arr[i] - arr[i - k];
      if sum >= min_sum { count += 1; }
    }
    count
  }
}