Today, we will solve the 3rd problem of the May LeetCoding Challenge 2021.

## Problem Statement

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.

**Example 1:**

```
**Input:** nums = [1,2,3,4]
**Output:** [1,3,6,10]
**Explanation:** Running sum is obtained as follows: [1, 1+2, 1+2+3, 1+2+3+4].
```

**Example 2:**

```
**Input:** nums = [1,1,1,1,1]
**Output:** [1,2,3,4,5]
**Explanation:** Running sum is obtained as follows: [1, 1+1, 1+1+1, 1+1+1+1, 1+1+1+1+1].
```

**Example 3:**

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

## Solution

This is a pretty easy problem. Here we have to find the running sum of an array. That means, for index i we have to find the sum of all elements from 0 to i-1 . It can be done by using sum variable to store the summation of each element index by index.

The code is given below.

Time complexity: O(n)

Space complexity: O(n)

where n is the size of the array

For the whole repository click the link below.

# LeetCode

I have been solving Leetcode problems for around a year or so. Suddenly I have developed a passion of writing tutorials for these problems. I am starting with Leetcode problem, in future I will try to make tutorials on Spring,Android,Java,Algorithms and many more.

Follow me on medium - https://sourav-saikia.medium.com

Follow me on dev.to - https://dev.to/sksaikia

Follow me on twitter - https://twitter.com/sourav__saikia

Connect on Linkedin - www.linkedin.com/in/sourav-kumar-saikia

The following table contains all the problems with their respective solution tutorials. I will try to add more articles to it soon.

Problem Name | Problem No | Article Links |
---|---|---|

Contains Duplicate | 217 | https://sourav-saikia.medium.com/leetcode-217-contains-duplicate-solution-36f48793bce0 |

Jewels and Stones | 771 | https://sourav-saikia.medium.com/leetcode-771-jewels-and-stones-e35a368fc37 |

Design Authentication Manager | 1797 | https://sourav-saikia.medium.com/leetcode-1797-design-authentication-manager-biweekly-contest-48-8ef4d82a220d |

## March LeetCoding Challenge

Problem Name | Problem No | Article Links |
---|---|---|

Distribute Candies | 575 | https://medium.com/dev-genius/march-leetcoding-challenge-2021-problem-1-distribute-candies-f37f66ea7ee9 |

Set Mismatch | 645 | https://sourav-saikia.medium.com/march-leetcoding-challenge-2021-day-2-set-mismatch-4abd5ee491c9 |

Missing Number | 268 | https://sourav-saikia.medium.com/march-leetcoding-challenge-2021-day-3-missing-number-ae8ee45a58cb |

Intersection of Two Linked Lists | 160 | https://sourav-saikia.medium.com/march-leetcoding-challenge-2021-day-4-intersection-of-two-linked-lists-a775449b5563 |

Average of Levels in Binary Tree | 637 | https://medium.com/dev-genius/march-leetcoding-challenge-2021-day-5-average-of-levels-in-binary-tree-ac886b2b42e8 |

Short Encoding of Words | 820 |

## Discussion (0)