From f38f4206f4d2959594926b1ae13c1a4a9600dee7 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gr=C3=A9gory=20Burri?= <gregory.burri@matisa.ch>
Date: Mon, 2 Dec 2019 08:39:41 +0100
Subject: [PATCH] Day 02

---
 src/common.rs |  4 ++--
 src/day01.rs  |  4 ++--
 src/day02.rs  | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.rs   | 15 ++++++++++----
 4 files changed, 72 insertions(+), 8 deletions(-)
 create mode 100644 src/day02.rs

diff --git a/src/common.rs b/src/common.rs
index 24c0c32..e87a0a2 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -1,6 +1,6 @@
 use std::fs;
 use std::path::Path;
 
-pub fn read_list_of_numbers<P: AsRef<Path>>(file: P) -> Vec<i32> {
-    fs::read_to_string(file).unwrap().lines().map(|line| line.parse::<i32>().unwrap()).collect()
+pub fn read_list_of_numbers<P: AsRef<Path>>(file: P, sep: &str) -> Vec<i32> {
+    fs::read_to_string(file).unwrap().split(sep).map(|line| line.parse::<i32>().unwrap()).collect()
 }
\ No newline at end of file
diff --git a/src/day01.rs b/src/day01.rs
index d62a298..ca1d470 100644
--- a/src/day01.rs
+++ b/src/day01.rs
@@ -31,13 +31,13 @@ mod tests {
         assert_eq!(mass_to_fuel(12), 2);
         assert_eq!(mass_to_fuel(14), 2);
         assert_eq!(mass_to_fuel(1969), 654);
-        assert_eq!(mass_to_fuel(100756), 33583);
+        assert_eq!(mass_to_fuel(100_756), 33583);
     }
 
     #[test]
     fn simple_cases_2() {
         assert_eq!(mass_to_fuel_2(14), 2);
         assert_eq!(mass_to_fuel_2(1969), 966);
-        assert_eq!(mass_to_fuel_2(100756), 50346);
+        assert_eq!(mass_to_fuel_2(100_756), 50346);
     }
 }
\ No newline at end of file
diff --git a/src/day02.rs b/src/day02.rs
new file mode 100644
index 0000000..76bc33e
--- /dev/null
+++ b/src/day02.rs
@@ -0,0 +1,57 @@
+pub fn execute_op_code_with_state_fixed(code : &mut [i32]) -> i32 {
+    code[1] = 12;
+    code[2] = 2;
+    execute_op_code(code)
+}
+
+fn execute_op_code(code : &mut [i32]) -> i32 {
+    let mut cursor = 0;
+    loop {
+        match code[cursor] {
+            1 => code[code[cursor + 3] as usize] = code[code[cursor + 1] as usize] + code[code[cursor + 2] as usize],
+            2 => code[code[cursor + 3] as usize] = code[code[cursor + 1] as usize] * code[code[cursor + 2] as usize],
+            99 => return code[0],
+            _ => panic!("Unkown code: {}", code[cursor])
+        }
+        cursor += 4;
+    }
+}
+
+pub fn find_noun_and_verb(code : &[i32]) -> i32 {
+    loop {
+        for noun in 0..=99 {
+            for verb in 0..=99 {
+                let mut code_copy = Vec::from(code);
+                code_copy[1] = noun;
+                code_copy[2] = verb;
+                if execute_op_code(&mut code_copy) == 19_690_720 {
+                    return 100 * noun + verb
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn simple_cases() {
+        let mut c1 = [1, 0, 0, 0, 99];
+        execute_op_code(&mut c1);
+        assert_eq!(c1[0], 2);
+
+        let mut c2 = [2, 3, 0, 3, 99];
+        execute_op_code(&mut c2);
+        assert_eq!(c2[3], 6);
+
+        let mut c3 = [2, 4, 4, 5, 99, 0];
+        execute_op_code(&mut c3);
+        assert_eq!(c3[5], 9801);
+
+        let mut c4 = [1, 1, 1, 4, 99, 5, 6, 0, 99];
+        execute_op_code(&mut c4);
+        assert_eq!(c4[0], 30);
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 5592192..83918d4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,14 +2,20 @@ use std::env;
 use std::time::Instant;
 
 mod day01;
+mod day02;
 mod common;
 
 fn day01() -> String {
-    let masses = common::read_list_of_numbers("data/day01.input");
+    let masses = common::read_list_of_numbers("data/day01.input", "\n");
     format!("part1: {}, part2: {}", day01::sum_mass_to_fuel(&masses), day01::sum_mass_to_fuel_2(&masses))
 }
 
-fn do_day(days: &Vec<fn() -> String>, day: usize) {
+fn day02() -> String {
+    let code = common::read_list_of_numbers("data/day02.input", ",");
+    format!("part1: {}, part2: {}", day02::execute_op_code_with_state_fixed(&mut Vec::from(&code[..])), day02::find_noun_and_verb(&code))
+}
+
+fn do_day(days: &[fn() -> String], day: usize) {
     let now = Instant::now();
     println!("Result of day {}: {} (time: {} μs)", day, days[day - 1](), now.elapsed().as_micros());
 }
@@ -18,13 +24,14 @@ fn main() {
     println!("https://adventofcode.com/2019");
 
     let days: Vec<fn() -> String> = vec!(
-        day01
+        day01,
+        day02
     );
 
     let args: Vec<String> = env::args().skip(1).collect();
 
     // No argument -> execute all day problems.
-    if args.len() == 0 {
+    if args.is_empty() {
         for i in 1..=days.len() {
             do_day(&days, i)
         }
-- 
2.45.2