commit a1b380717c8431dd3598481d47c5db316c3c0295
Author: george <george@wens.org.uk>
Date:   Tue Jun 18 15:06:38 2024 +0100

    add day 1 and 2 solutions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..8fdf18b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+target/
+input
diff --git a/day01/Cargo.lock b/day01/Cargo.lock
new file mode 100644
index 0000000..683c0b9
--- /dev/null
+++ b/day01/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day01"
+version = "0.1.0"
diff --git a/day01/Cargo.toml b/day01/Cargo.toml
new file mode 100644
index 0000000..5a61072
--- /dev/null
+++ b/day01/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "day01"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/day01/src/main.rs b/day01/src/main.rs
new file mode 100644
index 0000000..bcd6d65
--- /dev/null
+++ b/day01/src/main.rs
@@ -0,0 +1,30 @@
+use std::io::{self, BufRead};
+
+fn main() {
+    let nums: Vec<u64> = io::stdin()
+        .lock()
+        .lines()
+        .map(|line| line.unwrap().parse::<u64>().unwrap())
+        .collect();
+
+    let p1: u64 = nums.iter().map(|&num| mass_to_fuel(num)).sum();
+    let p2: u64 = nums.iter().map(|&num| fuel_for_fuel(num)).sum();
+
+    println!("P1: {}, P2: {}", p1, p2);
+}
+
+fn mass_to_fuel(mass: u64) -> u64 {
+    (mass / 3).saturating_sub(2)
+}
+
+fn fuel_for_fuel(fuel: u64) -> u64 {
+    let mut tot = 0;
+    let mut fuel = fuel;
+
+    while fuel > 0 {
+        fuel = mass_to_fuel(fuel);
+        tot += fuel;
+    }
+
+    tot
+}
diff --git a/day02/Makefile b/day02/Makefile
new file mode 100644
index 0000000..e69de29
diff --git a/day02/cmd/main.go b/day02/cmd/main.go
new file mode 100644
index 0000000..e1e705a
--- /dev/null
+++ b/day02/cmd/main.go
@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"intcode/internal/interpreter"
+	"intcode/internal/parser"
+)
+
+func main() {
+	sourceProgram, err := parser.ParseFile(nil)
+
+	if err != nil {
+		panic(err)
+	}
+
+	runProgram := make([]int, len(sourceProgram))
+
+	for x := 0; x < 100; x++ {
+		for y := 0; y < 100; y++ {
+			copy(runProgram, sourceProgram)
+
+            runProgram[1], runProgram[2] = x, y
+
+			interpreter := interpreter.Init(runProgram)
+
+			for !interpreter.Next() {}
+
+            if x == 12 && y == 2 {
+                fmt.Printf("Part 1: %v\n", runProgram[0])
+            }
+			if runProgram[0] == 19690720 {
+                fmt.Printf("Part 2: %02d%02d\n", x, y)
+			}
+		}
+	}
+}
diff --git a/day02/go.mod b/day02/go.mod
new file mode 100644
index 0000000..e902907
--- /dev/null
+++ b/day02/go.mod
@@ -0,0 +1,3 @@
+module intcode
+
+go 1.22.4
diff --git a/day02/internal/debugger/debugger.go b/day02/internal/debugger/debugger.go
new file mode 100644
index 0000000..fca119c
--- /dev/null
+++ b/day02/internal/debugger/debugger.go
@@ -0,0 +1 @@
+package debugger
diff --git a/day02/internal/interpreter/interpreter.go b/day02/internal/interpreter/interpreter.go
new file mode 100644
index 0000000..96b0dec
--- /dev/null
+++ b/day02/internal/interpreter/interpreter.go
@@ -0,0 +1,61 @@
+package interpreter
+
+import "fmt"
+
+type Interpreter struct {
+	program            []int
+	instructionPointer int
+}
+
+func Init(program []int) *Interpreter {
+    return &Interpreter {
+        program: program,
+        instructionPointer: 0,
+    }
+}
+
+func (i *Interpreter) Next() bool {
+	opcode := i.getValueAtIndex(i.instructionPointer)
+	ipIncrement := 1
+
+	switch opcode {
+	case 1:
+        i.add()
+        ipIncrement = 4
+	case 2:
+        i.mul()
+        ipIncrement = 4
+	case 99:
+		return true
+	default:
+		panic(fmt.Sprintf("unhandled opcode %v at IP %v", opcode, i.instructionPointer))
+	}
+
+	i.instructionPointer += ipIncrement
+
+	return false
+}
+
+func (i *Interpreter) getValueAtIndex(index int) int {
+    return i.program[index]
+}
+
+func (i *Interpreter) setValueAtIndex(index, value int) {
+    i.program[index] = value
+}
+
+func (i *Interpreter) add() {
+    resIndex := i.getValueAtIndex(i.instructionPointer + 3)
+    arg1Index := i.getValueAtIndex(i.instructionPointer + 1)
+    arg2Index := i.getValueAtIndex(i.instructionPointer + 2)
+
+    i.setValueAtIndex(resIndex, i.getValueAtIndex(arg1Index) + i.getValueAtIndex(arg2Index))
+}
+
+func (i *Interpreter) mul() {
+    resIndex := i.getValueAtIndex(i.instructionPointer + 3)
+    arg1Index := i.getValueAtIndex(i.instructionPointer + 1)
+    arg2Index := i.getValueAtIndex(i.instructionPointer + 2)
+
+    i.setValueAtIndex(resIndex, i.getValueAtIndex(arg1Index) * i.getValueAtIndex(arg2Index))
+}
diff --git a/day02/internal/interpreter/interpreter_test.go b/day02/internal/interpreter/interpreter_test.go
new file mode 100644
index 0000000..3576853
--- /dev/null
+++ b/day02/internal/interpreter/interpreter_test.go
@@ -0,0 +1 @@
+package interpreter
diff --git a/day02/internal/parser/parser.go b/day02/internal/parser/parser.go
new file mode 100644
index 0000000..9edffd6
--- /dev/null
+++ b/day02/internal/parser/parser.go
@@ -0,0 +1,48 @@
+package parser
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strconv"
+	"strings"
+)
+
+const DefaultFile = "input"
+
+func ParseFile(input *string) ([]int, error) {
+	if input == nil {
+
+		file := DefaultFile
+
+		if len(os.Args) == 2 {
+			file = os.Args[1]
+		}
+
+		inputFile, err := os.Open(file)
+		if err != nil {
+			return nil, fmt.Errorf("could not parse input file: %v", err)
+		}
+
+		fileData, err := io.ReadAll(inputFile)
+		if err != nil {
+			return nil, fmt.Errorf("could not read input file: %v", err)
+		}
+
+		fileStr := strings.TrimSpace(string(fileData))
+		input = &fileStr
+	}
+
+	strNums := strings.Split(*input, ",")
+	opcodes := make([]int, len(strNums))
+
+	for i, v := range strNums {
+		num, err := strconv.Atoi(v)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "WARNING: error parsing int from input, substring was %v", v)
+		}
+		opcodes[i] = num
+	}
+
+	return opcodes, nil
+}