# Leet Code Day #1480

Well, the time has come in my educational journey, I signed up for Leetcode. I heard about it all over the internet on Facebook, Reddit, and multiple slack groups. Honestly, I was beginning to overthink this website, how could so many people be plugging it. I am not really sure what held me back for so long, but I had a week off from school in between terms so I decided to give it a shot.

It was early Wednesday morning that I opened up the website, it took me a couple of minutes to navigate through and determine a good place to start. I am going to strive for solving a couple of problems a week, as it really helps my brain to wake up in the morning.

Here is the first problem that I tackled.

**1480. Running Sum of 1d Array**

I was asked to create a function that returns the running sum of a given array ‘nums’

**Thought process**:

This particular morning, I was feeling in the Java mood. It was what made my brain happy, so I went with that.

For this problem, I needed to create an array that takes the number in the index before and adds it to the current index. Sounds way more confusing than it actually is, ngl.

The first thing I knew I needed was a for loop, because I needed to be able to access each number in the array individually, which I know can easily be done with a *for* loop. I needed to start with index 1 (i could not start with 0, because I can not add the first number with the nonexistent one before) and go all the way through the length of the array, which in the constraints calls out the variable ‘nums.length”. After each pass I would need to add one to go to the next index and start the process over, That gave me

for( int i = 1; i< num.lengths; i++) {

}

*Int i = 1* initializing i as an int (integer) and setting it equal to 1

*I < num.lengths* so that we do not loop so many times that we run completely out of numbers, we need to stay within the bounds of the array.

*i++* after each pass through the loop we need to move over to the next index in the array

Next, I needed to figure out what goes inside of the loop. The current index that I was on needed to be equal to itself with the addition of the index previous. Which gave me this

Nums[i] += nums[i-1];

*Nums{i]* the index that we are working with

*+= * will add what comes after to what is before and set it equal to the before (expanded looked like:* nums[i] = nums{i] + nums[i-1];* )

*Nums[i-1]* the index previous

Then I just put it all together!

**My Solution**:

*class Solution {*

* public int[] runningSum(int[] nums) {*

for (int i = 1; i < nums.length; i++) {

nums[i] += nums[i - 1];

}

return nums;

* }*

*}*

**Results: **

** ****Runtime:** O(n)