Week 3: Arrays

How to do this

1. Go into your homework directory and run the command: git clone https://github.com/aethertap/typescript-template hw3
2. Enter the hw3 directory and type npm i
3. Type npm run br
   1. If it prints a bunch of stuff then ends up with "It works." you're good to go.
   2. If there are problems, let me know.
4. The starting point for your program will be in src/app.ts, but you can add other files and import them as needed. For now, app.ts is probably all you'll need.

Questions

1. How many elements does the array let a:number[]=[1,2,3,4,5]; contain? What is the index of the first element? The last?
2. This piece of code is supposed to make an array of five numbers that count from 1 to 5. What's wrong with it? What does it actually do?

   let a:number[] = [];
   for(i = 1; i <= 5; i = i + 1) {
   	a[i] = i;
   }
   

3. Write a function `function sum_series(n:number):number` that takes a number as an argument and returns the sum of all of the integers from 1 up to the number. You can use any clever tricks you may know to do this.