day 3

src/day1/mod.rs

@@ -14,7 +14,7 @@ pub fn run() {
     right.sort();
 
     let res = left.iter().zip(right.iter()).map(diff).sum::<i32>();
-    println!("1. {}", res);
+    println!("1. {}", res); // 1646452
 
     let left = HashSet::<i32>::from_iter(left.into_iter());
     let mut acc = 0;
@@ -24,7 +24,7 @@ pub fn run() {
         }
     }
 
-    println!("2. {}", acc);
+    println!("2. {}", acc); // 23609874
 }
 
 fn diff((a, b): (&i32, &i32)) -> i32 {

src/day2/mod.rs

@@ -8,14 +8,14 @@ pub fn run() {
         .filter_map(|mut line| is_safe(&mut line))
         .count();
 
+    println!("1. {}", safe); // 510
+
     let safe_corrected = input
         .lines()
         .map(ExpandedSplitWhitespaceNumbers::new)
         .filter_map(|mut line| is_safe_corrected(&mut line))
         .count();
-
-    println!("1. {}", safe);
-    println!("2. {}", safe_corrected);
+    println!("2. {}", safe_corrected); // 553
 }
 
 struct SplitWhitespaceNumbers<'a> {

src/day3/mod.rs

@@ -2,16 +2,66 @@ use std::fmt::Display;
 
 pub fn run() {
     let input = include_str!("input");
+    let mut modifier_disabled = DoModifier::disabled();
     let result = input
         .lines()
-        .map(|line| parse_instr(line))
+        .map(|line| parse_instr(line, &mut modifier_disabled))
         .map(|products| reduce_products(products))
         .sum::<u64>();
 
-    println!("1. {}", result);
+    println!("1. {}", result); // 189600467
+
+    let mut modifier_default = DoModifier::default();
+    let result = input
+        .lines()
+        .map(|line| parse_instr(line, &mut modifier_default))
+        .map(|products| reduce_products(products))
+        .sum::<u64>();
+
+    println!("2. {}", result); // 107069718
 }
 
-fn parse_instr(line: &str) -> Vec<u64> {
+struct DoModifier {
+    state: bool,
+    enabled: bool,
+}
+
+impl DoModifier {
+    fn disabled() -> Self {
+        DoModifier {
+            state: true,
+            enabled: false,
+        }
+    }
+
+    fn default() -> Self {
+        DoModifier {
+            state: true,
+            enabled: true,
+        }
+    }
+
+    fn should_mul(&self) -> bool {
+        if !self.enabled {
+            true
+        } else {
+            self.state
+        }
+    }
+
+    fn flip(&mut self, instr: Instr) {
+        if self.enabled {
+            self.state = match instr {
+                Instr::Do => true,
+                Instr::Dont => false,
+                _ => self.state,
+            }
+        }
+    }
+}
+
+fn parse_instr(line: &str, modifier: &mut DoModifier) -> Vec<u64> {
+    let mut instr = None;
     let mut state = ParseState::None;
     let mut first_num = Vec::new();
     let mut second_num = Vec::new();
@@ -19,17 +69,36 @@ fn parse_instr(line: &str) -> Vec<u64> {
     for (_i, c) in line.chars().enumerate() {
         let next = next_state(&state, c);
 
-        if let ParseState::ParamOne = next {
-            first_num.insert(0, c.to_digit(10).unwrap() as u64);
+        if let ParseState::D = next {
+            instr = Some(Instr::Do);
+        } else if let ParseState::T = next {
+            instr = Some(Instr::Dont);
+        } else if let ParseState::M = next {
+            instr = Some(Instr::Mul);
+        } else if let ParseState::ParamOne = next {
+            if modifier.should_mul() {
+                first_num.insert(0, c.to_digit(10).unwrap() as u64);
+            }
         } else if let ParseState::Comma = next {
-            finalize_number(&mut first_num);
+            if modifier.should_mul() {
+                finalize_number(&mut first_num);
+            }
         } else if let ParseState::ParamTwo = next {
             second_num.insert(0, c.to_digit(10).unwrap() as u64);
         } else if let ParseState::CloseParen = next {
-            finalize_number(&mut second_num);
-            res.push(first_num[0] * second_num[0]);
-            first_num.clear();
-            second_num.clear();
+            match instr {
+                Some(Instr::Mul) => {
+                    if modifier.should_mul() {
+                        finalize_number(&mut second_num);
+                        res.push(first_num[0] * second_num[0]);
+                    }
+                    first_num.clear();
+                    second_num.clear();
+                }
+                Some(instr) => modifier.flip(instr),
+                None => {}
+            }
+            instr = None;
         }
 
         if let ParseState::CloseParen = next {
@@ -65,8 +134,19 @@ fn reduce_products(products: Vec<u64>) -> u64 {
     products.iter().sum()
 }
 
+enum Instr {
+    Do,
+    Dont,
+    Mul,
+}
+
 enum ParseState {
     None,
+    D,
+    O,
+    N,
+    QUOTE,
+    T,
     M,
     U,
     L,
@@ -79,9 +159,48 @@ enum ParseState {
 
 fn next_state(state: &ParseState, c: char) -> ParseState {
     match state {
-        ParseState::None => {
+        ParseState::None | ParseState::CloseParen => {
             if c == 'm' {
                 ParseState::M
+            } else if c == 'd' {
+                ParseState::D
+            } else {
+                ParseState::None
+            }
+        }
+        ParseState::D => {
+            if c == 'o' {
+                ParseState::O
+            } else {
+                ParseState::None
+            }
+        }
+        ParseState::O => {
+            if c == '(' {
+                ParseState::OpenParen
+            } else if c == 'n' {
+                ParseState::N
+            } else {
+                ParseState::None
+            }
+        }
+        ParseState::N => {
+            if c == '\'' {
+                ParseState::QUOTE
+            } else {
+                ParseState::None
+            }
+        }
+        ParseState::QUOTE => {
+            if c == 't' {
+                ParseState::T
+            } else {
+                ParseState::None
+            }
+        }
+        ParseState::T => {
+            if c == '(' {
+                ParseState::OpenParen
             } else {
                 ParseState::None
             }
@@ -110,6 +229,8 @@ fn next_state(state: &ParseState, c: char) -> ParseState {
         ParseState::OpenParen => {
             if c.is_digit(10) {
                 ParseState::ParamOne
+            } else if c == ')' {
+                ParseState::CloseParen
             } else {
                 ParseState::None
             }
@@ -139,7 +260,6 @@ fn next_state(state: &ParseState, c: char) -> ParseState {
                 ParseState::None
             }
         }
-        ParseState::CloseParen => ParseState::None,
     }
 }
 
@@ -155,6 +275,11 @@ impl Display for ParseState {
             ParseState::Comma => write!(f, ","),
             ParseState::ParamTwo => write!(f, "ParamTwo"),
             ParseState::CloseParen => write!(f, ")"),
+            ParseState::D => write!(f, "D"),
+            ParseState::O => write!(f, "O"),
+            ParseState::N => write!(f, "N"),
+            ParseState::QUOTE => write!(f, "'"),
+            ParseState::T => write!(f, "T"),
         }
     }
 }