Sum of all odd length subarrays

Array Math Prefix Sum

83.9% acceptance

Feb 25, 2026

3880

328

Given an array of positive integers arr, return the sum of all possible odd-length subarrays of arr.

Solution

Rust

Time O(n²)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn sum_odd_length_subarrays(arr: Vec<i32>) -> i32 {
    let n = arr.len();
    let mut sum = 0;
    for i in 0..n {
      let mut len = 1;
      while i + len <= n {
        sum += arr[i..i + len].iter().sum::<i32>();
        len += 2;
      }
    }
    sum
  }
}