Day 15 (Golang)

15-rambunctiousRecitation/README.md

@@ -20,6 +20,23 @@ Test cases
 1.6 pass
 2.1 pass
 
+Answers
+Part 1: 206
+Part 2: 955
+
+❯ go run .\go\
+AoC 2020: day 15 - Rambunctious Recitation
+Go go1.15.2
+
+Test cases
+1.1 pass
+1.2 pass
+1.3 pass
+1.4 pass
+1.5 pass
+1.6 pass
+2.1 pass
+
 Answers
 Part 1: 206
 Part 2: 955

15-rambunctiousRecitation/go/challenge/common.go

@@ -0,0 +1,47 @@
+package challenge
+
+import (
+	"strconv"
+	"strings"
+)
+
+func findValueN(instr string, threshold int) int {
+	var inp []int
+	for _, x := range strings.Split(strings.TrimSpace(instr), ",") {
+		i, err := strconv.Atoi(x)
+		if err != nil {
+			panic(err)
+		}
+		inp = append(inp, i)
+	}
+
+	indexes := make(map[int]int)
+
+	for i, n := range inp {
+		indexes[n] = i
+	}
+
+	for len(inp) < threshold {
+		c := len(inp) - 1
+		previousNumber := inp[c]
+
+		var previousOccuranceIndex int
+		val, found := indexes[previousNumber]
+		if !found {
+			previousOccuranceIndex = -1
+		} else {
+			previousOccuranceIndex = val
+		}
+
+		var newNumber int
+
+		if previousOccuranceIndex != -1 {
+			newNumber = c - previousOccuranceIndex
+		}
+
+		indexes[previousNumber] = c
+		inp = append(inp, newNumber)
+	}
+
+	return inp[len(inp)-1]
+}

15-rambunctiousRecitation/go/challenge/partOne.go

@@ -0,0 +1,5 @@
+package challenge
+
+func PartOne(instr string) int {
+	return findValueN(instr, 2020)
+}

15-rambunctiousRecitation/go/challenge/partTwo.go

@@ -0,0 +1,5 @@
+package challenge
+
+func PartTwo(instr string) int {
+	return findValueN(instr, 30000000)
+}

15-rambunctiousRecitation/go/main.go

@@ -0,0 +1,100 @@
+package main
+
+import (
+	"adventOfCode/15-rambunctiousRecitation/go/challenge"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"runtime"
+	"strconv"
+
+	"github.com/fatih/color"
+)
+
+func main() {
+	var infoStruct info
+	{
+		inb, err := ioutil.ReadFile("info.json")
+		if err != nil {
+			fmt.Println("Error: could not open info.json")
+			os.Exit(-1)
+		}
+		err = json.Unmarshal(inb, &infoStruct)
+		if err != nil {
+			fmt.Println("Error: could not parse info.json")
+			os.Exit(-1)
+		}
+	}
+
+	var (
+		year  = infoStruct.Year
+		day   = infoStruct.Day
+		title = infoStruct.Title
+	)
+
+	fmt.Fprintf(color.Output, "%s: day %s - %s\n", color.YellowString("AoC "+year), color.BlueString(day), title)
+	fmt.Fprintf(color.Output, "Go %s\n\n", color.BlueString(runtime.Version()))
+
+	var challengeInput string
+	{
+		inb, err := ioutil.ReadFile("input.txt")
+		if err != nil {
+			fmt.Println("Error: could not open input.txt")
+			os.Exit(-1)
+		}
+		challengeInput = string(inb)
+	}
+
+	runTests(infoStruct)
+
+	fmt.Println("Answers")
+	fmt.Fprintf(color.Output, "Part %s: %s\n", color.BlueString("1"), color.BlueString(strconv.Itoa(challenge.PartOne(challengeInput))))
+	fmt.Fprintf(color.Output, "Part %s: %s\n", color.BlueString("2"), color.BlueString(strconv.Itoa(challenge.PartTwo(challengeInput))))
+
+}
+
+type tc struct {
+	Input    string `json:"input"`
+	Expected int    `json:"expected"`
+}
+
+type info struct {
+	Year      string `json:"year"`
+	Day       string `json:"day"`
+	Title     string `json:"title"`
+	TestCases struct {
+		One []tc `json:"one"`
+		Two []tc `json:"two"`
+	} `json:"testCases"`
+}
+
+func runTests(infoStruct info) {
+
+	if len(infoStruct.TestCases.One) == 0 && len(infoStruct.TestCases.Two) == 0 {
+		fmt.Println("Info: no test cases specified. Skipping tests")
+		fmt.Println()
+		return
+	}
+
+	fmt.Println("Test cases")
+
+	rt := func(tcs []tc, f func(string) int, n string) {
+		for i, tc := range tcs {
+			fmt.Fprintf(color.Output, "%s ", color.BlueString(n+"."+strconv.Itoa(i+1)))
+			result := f(tc.Input)
+			if result == tc.Expected {
+				fmt.Fprintf(color.Output, "%s", color.GreenString("pass"))
+			} else {
+				fmt.Fprintf(color.Output, "%s (got %s, expected %s)", color.RedString("fail"), color.BlueString(strconv.Itoa(result)), color.BlueString(strconv.Itoa(tc.Expected)))
+			}
+			fmt.Println()
+		}
+	}
+
+	rt(infoStruct.TestCases.One, challenge.PartOne, "1")
+	rt(infoStruct.TestCases.Two, challenge.PartTwo, "2")
+
+	fmt.Println()
+
+}