Advent of Code 2021 | Day 2 | Solutions in Python3

December 2, 2021

Advent of Code 2021

Tanishq Chaudhary

These are the solutions to today’s aka day 2’s Advent of Code 2021 in Python3. They are pretty self explanatory. Problem Link.

Contents hide

Problem Setup

Part 1 Solution

Part 2 Solution

Problem Setup

input: a list of commands in the format command value
where each command is one of forward or up or down
output: multiple horizontal distance and depth

Part 1 Solution

Given how the forward, up and down change we get something as shown below:

def get_input():
    data = []
    with open("input.txt") as f:
        data = f.readlines()
    return data


def solve(commands):
    horizontal = 0
    depth = 0

    for full_command in commands:
        command, value = full_command.split()
        value = int(value)

        if command == "forward":
            horizontal += value
        elif command == "up":
            depth -= value
        elif command == "down":
            depth += value

    return horizontal * depth


print(solve(get_input()))

Part 2 Solution

Given how the forward, up and down change we get something as shown below:

from collections import defaultdict


def get_input():
    data = []
    with open("input.txt") as f:
        data = f.readlines()
    return data


def solve(commands):
    horizontal = 0
    depth = 0
    aim = 0

    for full_command in commands:
        command, value = full_command.split()
        value = int(value)

        if command == "forward":
            horizontal += value
            depth += aim * value
        elif command == "up":
            aim -= value
        elif command == "down":
            aim += value

    return horizontal * depth


print(solve(get_input()))

implementation