Day 2

.gitignore

@@ -1,3 +1,4 @@
 bin/
 zig-out/
 zig-cache/
+target/

day2/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day2"
+version = "0.1.0"

day2/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day2"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day2/input

@@ -0,0 +1 @@
+1,0,0,3,1,1,2,3,1,3,4,3,1,5,0,3,2,1,10,19,1,9,19,23,1,13,23,27,1,5,27,31,2,31,6,35,1,35,5,39,1,9,39,43,1,43,5,47,1,47,5,51,2,10,51,55,1,5,55,59,1,59,5,63,2,63,9,67,1,67,5,71,2,9,71,75,1,75,5,79,1,10,79,83,1,83,10,87,1,10,87,91,1,6,91,95,2,95,6,99,2,99,9,103,1,103,6,107,1,13,107,111,1,13,111,115,2,115,9,119,1,119,6,123,2,9,123,127,1,127,5,131,1,131,5,135,1,135,5,139,2,10,139,143,2,143,10,147,1,147,5,151,1,151,2,155,1,155,13,0,99,2,14,0,0

day2/src/main.rs

@@ -0,0 +1,105 @@
+fn main() {
+    let contents = std::fs::read_to_string("input")
+        .expect("Failed to read file 'input'");
+    let it = contents.split(",");
+    let mut program = Vec::new();
+    for val in it {
+        if val.ends_with('\n') {
+            let mut s = String::from(val);
+            s.pop();
+            program.push(s.parse::<i32>().unwrap());
+        }
+        else {
+            program.push(val.parse::<i32>().unwrap());
+        }
+    }
+
+    // Create a copy of the memory to refresh from
+    let backup = program.clone();
+
+    // Modify state for part 1
+    program[1] = 12;
+    program[2] = 2;
+    simulate(&mut program);
+    println!("[Part 1] The value at position 0 is: {}", program[0]);
+
+    let mut noun = 0;
+    while noun < 100 {
+        let mut verb = 0;
+        while verb < 100 {
+            program = backup.clone();
+            program[1] = noun;
+            program[2] = verb;
+            simulate(&mut program);
+            //println!("Noun {}, verb {}: {}", noun, verb, program[0]);
+            if program[0] == 19690720 {
+                println!("[Part 2] noun {}, verb {}, sum {}", noun, verb, 100*noun+verb);
+                break;
+            }
+            verb += 1;
+        }
+        noun += 1;
+    }
+}
+
+fn simulate(v: &mut Vec<i32>) {
+    let mut pos = 0;
+    loop {
+        let code = v[pos];
+        if code == 1 {
+            let i1 = v[pos+1] as usize;
+            let i2 = v[pos+2] as usize;
+            let idest = v[pos+3] as usize;
+            v[idest] = v[i1] + v[i2];
+            pos += 4;
+            continue;
+        }
+        else if code == 2 {
+            let i1 = v[pos+1] as usize;
+            let i2 = v[pos+2] as usize;
+            let idest = v[pos+3] as usize;
+            v[idest] = v[i1] * v[i2];
+            pos += 4;
+            continue;
+        }
+        else if code == 99 {
+            break;
+        }
+        else {
+            panic!("Unknown opcode");
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_op_1() {
+        let mut program = vec![1, 0, 0, 0, 99];
+        simulate(&mut program);
+        assert_eq!(program[0], 2);
+    }
+
+    #[test]
+    fn test_op_2() {
+        let mut program = vec![2, 3, 0, 3, 99];
+        simulate(&mut program);
+        assert_eq!(program[3], 6);
+    }
+
+    #[test]
+    fn test_case_3() {
+        let mut program = vec![2,4,4,5,99,0];
+        simulate(&mut program);
+        assert_eq!(program[program.len() - 1], 9801);
+    }
+
+    #[test]
+    fn test_case_4() {
+        let mut program = vec![1,1,1,4,99,5,6,0,99];
+        simulate(&mut program);
+        assert_eq!(program[0], 30);
+        assert_eq!(program[4], 2);
+    }
+}