Day 1 - Advent Of Code 2022

The problem statement

The jungle must be too overgrown and difficult to navigate in vehicles or access from the air; the Elves' expedition traditionally goes on foot. As your boats approach land, the Elves begin taking inventory of their supplies. One important consideration is food - in particular, the number of Calories each Elf is carrying (your puzzle input).

The Elves take turns writing down the number of Calories contained by the various meals, snacks, rations, etc. that they've brought with them, one item per line. Each Elf separates their own inventory from the previous Elf's inventory (if any) by a blank line.

In case the Elves get hungry and need extra snacks, they need to know which Elf to ask: they'd like to know how many Calories are being carried by the Elf carrying the most Calories. In the example above, this is 24000 (carried by the fourth Elf).

Find the Elf carrying the most Calories. How many total Calories is that Elf carrying?

Examples:

For example, suppose the Elves finish writing their items' Calories and end up with the following list:

1000
2000
3000

4000

5000
6000

7000
8000
9000

10000

This list represents the Calories of the food carried by five Elves:

The first Elf is carrying food with 1000, 2000, and 3000 Calories, a total of 6000 Calories. The second Elf is carrying one food item with 4000 Calories. The third Elf is carrying food with 5000 and 6000 Calories, a total of 11000 Calories. The fourth Elf is carrying food with 7000, 8000, and 9000 Calories, a total of 24000 Calories. The fifth Elf is carrying one food item with 10000 Calories.

Understanding the problem

When you read the question a few times, don't make the same mistake that I did.

It's asking for us to return the HIGHEST NUMBER OF CALORIES not the index of the elf which has the most calories.

To do that we know this:

1. If we split this input by empty line we can get an array of elves.
2. We can then split each item in our array by new line to get each value.
3. Then we can add up the total amount for each elf.
4. As we go through the array, keep track of the highest calories.
5. Return the highest amount.

Let's see how we do that in code.

Code

function elfCarryingMostCalories(input: string) {
  // split the input by blank lines and begin reducing the array.
  return input.split("\n\n").reduce((acc, curr, index) => {
    // iterate each elf via its array elem, split the array by new line to get each calorie row for that elf. Grab the total.
    const calories = curr
      .split("\n")
      .reduce((acc, curr) => acc + Number(curr), 0);
    // if the elf has a higher amount of calories than the existing highest amount, override it.
    if (calories > acc) {
      acc = calories;
    }
    return acc;
  }, 0);
}

Code Explanation

This code is pretty self explanatory.

Key takeaways

1. Array reduce to the rescue! Also you can get the index from reduce. Didn't know that before!