2020 Day 15 Complete

2020/day14/main.go

@@ -8,7 +8,7 @@ import (
 )
 
 func main() {
-	fmt.Println("# Day 13")
+	fmt.Println("# Day 14")
 	inp := h.StdinToStringSlice()
 	vsn := h.Atoi(h.OptArgNumber(1, "1"))
 	if vsn == 1 {

2020/day15/input

@@ -0,0 +1 @@
+0,8,15,2,12,1,4

2020/day15/main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	fmt.Println("# Day 15")
+	inp := h.StdinToString()
+	fmt.Println("## Part 1")
+	dumbFind(inp, 2020)
+	fmt.Println("## Part 2")
+	dumbFind(inp, 30000000)
+}
+
+func dumbFind(inp string, num int) {
+	start := strings.Split(inp, ",")
+	rem := make(map[int][]int)
+	turn := 1
+	var last int
+	for k := range start {
+		last = h.Atoi(start[k])
+		rem[last] = []int{turn}
+		turn++
+	}
+	for turn <= num {
+		last = speakNext(last, turn, &rem)
+		turn++
+	}
+	fmt.Println("Answer:", last)
+}
+
+func speakNext(prev int, turn int, rem *map[int][]int) int {
+	wrk := *rem
+	if len(wrk[prev]) == 1 {
+		wrk[0] = append(wrk[0], turn)
+		return 0
+	} else {
+		last := wrk[prev][len(wrk[prev])-2]
+		diff := (turn - 1) - last
+		wrk[diff] = append(wrk[diff], turn)
+		return diff
+	}
+}

2020/day15/testinput

@@ -0,0 +1 @@
+0,3,6