day 2 solution

2022/src/days/day2.rs

@@ -0,0 +1,101 @@
+use anyhow::{anyhow, Result};
+use std::fs;
+
+enum Pieces {
+    Rock,
+    Paper,
+    Scissors,
+}
+
+enum EndStates {
+    Lose,
+    Draw,
+    Win,
+}
+
+pub fn run() -> Result<()> {
+    let file_contents = fs::read_to_string("day2.txt")?;
+    let lines = file_contents.lines();
+    let mut part_one_scores: Vec<u32> = Vec::with_capacity(1000);
+    let mut part_two_scores: Vec<u32> = Vec::with_capacity(1000);
+
+    for line in lines {
+        let opponent = match &line[0..1] {
+            "A" => Pieces::Rock,
+            "B" => Pieces::Paper,
+            "C" => Pieces::Scissors,
+            _ => return Err(anyhow!("Invalid piece")),
+        };
+
+        let player_one = match &line[2..3] {
+            "X" => Pieces::Rock,
+            "Y" => Pieces::Paper,
+            "Z" => Pieces::Scissors,
+            _ => return Err(anyhow!("Invalid player piece")),
+        };
+
+        let game_result = match opponent {
+            Pieces::Rock => match player_one {
+                Pieces::Rock => EndStates::Draw,
+                Pieces::Paper => EndStates::Win,
+                Pieces::Scissors => EndStates::Lose,
+            },
+            Pieces::Paper => match player_one {
+                Pieces::Rock => EndStates::Lose,
+                Pieces::Paper => EndStates::Draw,
+                Pieces::Scissors => EndStates::Win,
+            },
+            Pieces::Scissors => match player_one {
+                Pieces::Rock => EndStates::Win,
+                Pieces::Paper => EndStates::Lose,
+                Pieces::Scissors => EndStates::Draw,
+            },
+        };
+
+        let player_score = match player_one {
+            Pieces::Rock => 1,
+            Pieces::Paper => 2,
+            Pieces::Scissors => 3,
+        };
+        part_one_scores.push(player_score);
+        let game_score = match game_result {
+            EndStates::Lose => 0,
+            EndStates::Draw => 3,
+            EndStates::Win => 6,
+        };
+        part_one_scores.push(game_score);
+
+        let part_two_goal = match &line[2..3] {
+            "X" => EndStates::Lose,
+            "Y" => EndStates::Draw,
+            "Z" => EndStates::Win,
+            _ => return Err(anyhow!("Invalid part two goal char")),
+        };
+
+        let part_two_score = match part_two_goal {
+            EndStates::Lose => match opponent {
+                Pieces::Rock => 3 + 0,
+                Pieces::Paper => 1 + 0,
+                Pieces::Scissors => 2 + 0,
+            },
+            EndStates::Draw => match opponent {
+                Pieces::Rock => 1 + 3,
+                Pieces::Paper => 2 + 3,
+                Pieces::Scissors => 3 + 3,
+            },
+            EndStates::Win => match opponent {
+                Pieces::Rock => 2 + 6,
+                Pieces::Paper => 3 + 6,
+                Pieces::Scissors => 1 + 6,
+            },
+        };
+        part_two_scores.push(part_two_score);
+    }
+
+    let part_one_sum: u32 = part_one_scores.into_iter().sum();
+    let part_two_sum: u32 = part_two_scores.into_iter().sum();
+    println!("part one {}", part_one_sum);
+    println!("part two {}", part_two_sum);
+
+    Ok(())
+}

2022/src/days/mod.rs

@@ -1 +1,2 @@
 pub mod day1;
+pub mod day2;

2022/src/main.rs

@@ -12,6 +12,9 @@ fn run_day(number: i32) -> Result<()> {
         1 => {
             days::day1::run()?;
         }
+        2 => {
+            days::day2::run()?;
+        }
         _ => return Err(anyhow!("Invalid day provided")),
     }
     Ok(())

2022/tests/day2.txt

@@ -0,0 +1,3 @@
+A Y
+B X
+C Z