From d655a146082321096aa686368850efd807192cbf Mon Sep 17 00:00:00 2001 From: Justin Wernick Date: Tue, 21 Dec 2021 09:35:55 +0200 Subject: Day 21 part 1 --- inputs/day_21.txt | 2 ++ src/bin/day_21.rs | 41 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+) create mode 100644 inputs/day_21.txt create mode 100644 src/bin/day_21.rs diff --git a/inputs/day_21.txt b/inputs/day_21.txt new file mode 100644 index 0000000..bfb2937 --- /dev/null +++ b/inputs/day_21.txt @@ -0,0 +1,2 @@ +Player 1 starting position: 7 +Player 2 starting position: 5 diff --git a/src/bin/day_21.rs b/src/bin/day_21.rs new file mode 100644 index 0000000..e937bcb --- /dev/null +++ b/src/bin/day_21.rs @@ -0,0 +1,41 @@ +use nom::{ + bytes::complete::tag, + character::complete::u32 as nom_u32, + combinator::map, + sequence::{preceded, tuple}, + IResult, +}; +use std::fs; + +fn main() -> Result<(), Box> { + let input = fs::read_to_string("inputs/day_21.txt")?; + let mut player_positions = parse_starting_positions(&input).unwrap().1; + let mut player_scores = [0, 0]; + let mut dice = (1..=100).cycle().enumerate().peekable(); + let mut player_turn = 0; + while player_scores[0] < 1000 && player_scores[1] < 1000 { + let dice_roll: u32 = dice.by_ref().take(3).map(|(_, roll)| roll).sum(); + player_positions[player_turn] = (player_positions[player_turn] + dice_roll) % 10; + if player_positions[player_turn] == 0 { + player_positions[player_turn] = 10; + } + player_scores[player_turn] += player_positions[player_turn]; + player_turn = (player_turn + 1) % 2; + } + let losing_score = player_scores.iter().min().cloned().unwrap_or(0); + let dice_roll_count = dice.peek().unwrap().0; + dbg!((losing_score, dice_roll_count)); + dbg!(losing_score * dice_roll_count as u32); + + Ok(()) +} + +fn parse_starting_positions(input: &str) -> IResult<&str, [u32; 2]> { + map( + tuple(( + preceded(tag("Player 1 starting position: "), nom_u32), + preceded(tag("\nPlayer 2 starting position: "), nom_u32), + )), + |(a, b)| [a, b], + )(input) +} -- cgit v1.2.3