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#1480
Easy Algorithms

Running sum of 1d array

Array Prefix Sum
86.9% acceptance
Feb 25, 2026
8720
371
Given an array nums. We define a running sum of an array as runningSum[i] = sum(nums[0]…nums[i]). Return the running sum of nums.

Solution

Rust
Time O(n)
Space O(1)
LeetCode
solution.rs
impl Solution {
  pub fn running_sum(mut nums: Vec<i32>) -> Vec<i32> {
    for i in 1..nums.len() {
      nums[i] += nums[i - 1];
    }
    nums
  }
}