AoC 2020: day4

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

2019-go/day_02/day_02.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"encoding/csv"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+)
+
+func readValues(fileName string) []int {
+	file, err := os.Open(fileName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+
+	r := csv.NewReader(file)
+
+	recordsMatrix, err := r.ReadAll()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	values := make([]int, len(recordsMatrix[0]))
+
+	for i, value := range recordsMatrix[0] {
+		values[i], err = strconv.Atoi(value)
+		if err != nil {
+			log.Printf("Error converting line to int: %v", err)
+		}
+	}
+
+	return values
+}
+
+func restore1202(values []int) []int {
+	restoredValues := append(values[:0:0], values...)
+
+	restoredValues[1] = 12
+	restoredValues[2] = 2
+
+	return restoredValues
+}
+
+func findNounVerb(values []int) int {
+	testValues := append(values[:0:0], values...)
+	for noun := 0; noun < 100; noun++ {
+		for verb := 0; verb < 100; verb++ {
+			testValues[1] = noun
+			testValues[2] = verb
+			output := runIntcode(testValues)
+			if output == 19690720 {
+				return 100*noun + verb
+			}
+		}
+	}
+	return -1
+}
+
+func runIntcode(values []int) int {
+	processedValues := append(values[:0:0], values...)
+loop:
+	for i := 0; i < len(processedValues); i += 4 {
+		num1 := processedValues[processedValues[i+1]]
+		num2 := processedValues[processedValues[i+2]]
+		pos := processedValues[i+3]
+
+		switch processedValues[i] {
+		case 1:
+			processedValues[pos] = num1 + num2
+		case 2:
+			processedValues[pos] = num1 * num2
+		case 99:
+			break loop
+		default:
+			log.Printf("Error evaluating opcode %d\n", processedValues[i])
+			return -1
+		}
+	}
+	return processedValues[0]
+}
+
+func main() {
+	values := readValues("./input")
+
+	// Part 1
+	restoredValues := restore1202(values)
+	initialValue := runIntcode(restoredValues)
+	fmt.Printf("Part 1: %d\n", initialValue)
+
+	//Part 2
+	nounVerb := findNounVerb(values)
+	fmt.Printf("Part 2: %d\n", nounVerb)
+}

2019-go/day_02/input

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