AoC 21-02

import pandas as pd

data = pd.read_csv(
    "inputs/2021/02/data.csv",
    sep=" ",
    header=None,
    names=["direction", "n"],
    dtype=dict(direction=str, n=int)
)

# Part 1
direction_counts = data.groupby("direction").n.sum()
part_1 = (direction_counts["down"] - direction_counts["up"]) * direction_counts["forward"]
print(f"Part 1: {part_1:,d}")

# Part 2
data = data.pivot(columns="direction", values="n").fillna(0)
data["aim"] = (data.down - data.up).cumsum()
depth = (data.aim * data.forward).sum()
horizontal = data.forward.sum()

part_2 = depth * horizontal
print(f"Part 2: {part_2:,.0f}")