From 0fb63e65e95d0476b96c35602e105c0f8af56072 Mon Sep 17 00:00:00 2001
From: David Lenfesty <lenfesty@ualberta.ca>
Date: Sat, 4 Dec 2021 12:08:50 -0700
Subject: [PATCH] Finished day 4

---
 src/day2.rs |   1 +
 src/day4.rs | 135 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs |   7 +++
 3 files changed, 143 insertions(+)
 create mode 100644 src/day4.rs

diff --git a/src/day2.rs b/src/day2.rs
index 63d8dd3..1e13e9c 100644
--- a/src/day2.rs
+++ b/src/day2.rs
@@ -1,5 +1,6 @@
 struct Position {
     pub x: i64,
+    #[allow(dead_code)]
     pub y: i64,
     pub z: i64,
 }
diff --git a/src/day4.rs b/src/day4.rs
new file mode 100644
index 0000000..abc48b6
--- /dev/null
+++ b/src/day4.rs
@@ -0,0 +1,135 @@
+use std::convert::TryInto;
+
+struct BingoBoard {
+    board: [[u8; 5]; 5],
+    marked: [[bool; 5]; 5],
+    bingo: bool,
+}
+
+impl BingoBoard {
+    fn new(board: [[u8; 5]; 5]) -> Self {
+        Self {
+            board,
+            marked: [[false; 5]; 5],
+            bingo: false,
+        }
+    }
+
+    /// Checks to see if bingo has been achieved.
+    ///
+    /// Returns true if any row or column is fully marked. (Ignores diagonals)
+    fn check_bingo(&mut self) -> bool {
+        // Check rows
+        for row in self.marked {
+            if row.iter().all(|marked| *marked) {
+                self.bingo = true;
+                return true;
+            }
+        }
+
+        // Check columns
+        for i in 0..self.marked.len() {
+            if self.marked.iter().map(|row| row[i]).all(|marked| marked) {
+                self.bingo = true;
+                return true;
+            }
+        }
+
+        false
+    }
+
+    fn is_bingo(&self) -> bool {
+        self.bingo
+    }
+
+    /// Checks number for existance on board and marks off any instances of it.
+    fn check_number(&mut self, number: u8) {
+        for i in 0..self.board.len() {
+            for j in 0..self.board[i].len() {
+                if self.board[i][j] == number {
+                    self.marked[i][j] = true;
+                }
+            }
+        }
+    }
+
+    // Scores board based on input number
+    fn score(&self, number: u8) -> usize {
+        let mut score = 0usize;
+        for i in 0..self.board.len() {
+            for j in 0..self.board[i].len() {
+                if !self.marked[i][j] {
+                    score += self.board[i][j] as usize;
+                }
+            }
+        }
+
+        score * number as usize
+    }
+}
+
+fn parse_input(input: String) -> (Vec<u8>, Vec<BingoBoard>) {
+    let mut lines = input.lines();
+
+    let input: Vec<u8> = lines
+        .next()
+        .unwrap()
+        .split(',')
+        .map(|s| str::parse::<u8>(s).unwrap())
+        .collect();
+
+    // Keep building boards until we don't have any more lines to parse
+    let mut boards = Vec::<BingoBoard>::new();
+    while let Some(_) = lines.next() {
+        let mut board = [[0u8; 5]; 5];
+        for i in 0..board.len() {
+            let line: Vec<u8> = lines
+                .next()
+                .unwrap()
+                .split_whitespace()
+                .map(|s| str::parse::<u8>(s).unwrap())
+                .collect();
+            board[i] = line.try_into().unwrap();
+        }
+
+        boards.push(BingoBoard::new(board));
+    }
+
+    (input, boards)
+}
+
+pub fn part1(input: String) {
+    let (input, mut boards) = parse_input(input);
+
+    for call in input {
+        // Mark and check boards
+        // NOTE: making big assumption here that only one board wins
+        for board in &mut boards {
+            board.check_number(call);
+
+            if board.check_bingo() {
+                println!("Final score: {}", board.score(call));
+                return;
+            }
+        }
+    }
+}
+
+pub fn part2(input: String) {
+    let (input, mut boards) = parse_input(input);
+
+    let mut final_score = 0usize;
+    for call in input {
+        for board in &mut boards {
+            if !board.is_bingo() {
+                board.check_number(call);
+
+                if board.check_bingo() {
+                    final_score = board.score(call);
+                }
+            }
+        }
+    }
+
+    println!("Last winner's score: {}", final_score);
+}
diff --git a/src/main.rs b/src/main.rs
index 65dd063..021221d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,7 @@ use clap::{App, Arg};
 mod day1;
 mod day2;
 mod day3;
+mod day4;
 
 fn main() {
     let matches = App::new("AOC 2021 Code")
@@ -34,6 +35,7 @@ fn main() {
 
     let input = read_input(day).unwrap();
 
+    // TODO macro-ify
     match day {
         1 => match part {
             1 => day1::day1_p1(input),
@@ -50,6 +52,11 @@ fn main() {
             2 => day3::part2(input),
             _ => (),
         },
+        4 => match part {
+            1 => day4::part1(input),
+            2 => day4::part2(input),
+            _ => (),
+        },
         _ => println!("Day {} not completed yet!", day),
     }
 }