DEV Community

loading...
Cover image for Algorithms Problem Solving: Running Array Sum

Algorithms Problem Solving: Running Array Sum

teekay profile image TK Originally published at leandrotk.github.io ・1 min read

This post is part of the Algorithms Problem Solving series.

Problem description

This is the Running Array Sum problem. The description looks like this:

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.

Examples

Input: nums = [1,2,3,4]
Output: [1,3,6,10]

Input: nums = [1,1,1,1,1]
Output: [1,2,3,4,5]

Input: nums = [3,1,2,10,1]
Output: [3,4,6,16,17]

Solution

The idea here is to cache the sum of the numbers while iterating through the list. For each number, add to the sum and then add the sum to the result list.

def running_sum(nums):
    sum = 0
    result = []

    for num in nums:
        sum += num
        result.append(sum)

    return result

Resources

Discussion (0)

pic
Editor guide