Find the score of all prefixes of an array

Array Prefix Sum

72.8% acceptance

Feb 25, 2026

364

We define the conversion array conver of an array arr as follows: conver[i] = arr[i] + max(arr[0..i]) where max(arr[0..i]) is the maximum value of arr[j] over 0 <= j <= i. We also define the score of an array arr as the sum of the values of the conversion array of arr. Given a 0-indexed integer array nums of length n, return an array ans of length n where ans[i] is the score of the prefix nums[0..i].

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn find_prefix_score(nums: Vec<i32>) -> Vec<i64> {
    let n = nums.len();
    let mut ans = vec![0i64; n];
    let mut running_max = 0i64;
    let mut running_score = 0i64;

    for i in 0..n {
      let v = nums[i] as i64;
      if v > running_max {
        running_max = v;
      }
      running_score += v + running_max;
      ans[i] = running_score;
    }
    ans
  }
}