2022 Day 20 Complete!

2022/day20/main.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"fmt"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+type Node struct {
+	value int
+	prev  *Node
+	next  *Node
+}
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	part2(inp)
+}
+
+func part1(inp []string) {
+	var list []*Node
+	var first *Node
+	for i := range inp {
+		n := &Node{value: h.Atoi(inp[i])}
+		if n.value == 0 {
+			first = n
+		}
+		list = append(list, n)
+	}
+	initList(list)
+	mixAll(list)
+	fmt.Println("# Part 1")
+	fmt.Println(getCoords(first))
+}
+
+func part2(inp []string) {
+	key := 811589153
+	var list []*Node
+	var first *Node
+	for i := range inp {
+		n := &Node{value: h.Atoi(inp[i]) * key}
+		if n.value == 0 {
+			first = n
+		}
+		list = append(list, n)
+	}
+	initList(list)
+	for i := 0; i < 10; i++ {
+		mixAll(list)
+	}
+	fmt.Println("# Part 2")
+	fmt.Println(getCoords(first))
+}
+
+func initList(list []*Node) {
+	list[0].prev = list[len(list)-1]
+	list[len(list)-1].next = list[0]
+	for i := 1; i < len(list); i++ {
+		list[i].prev = list[i-1]
+		list[i-1].next = list[i]
+	}
+}
+
+func move(n *Node, count int) *Node {
+	for count < 0 {
+		n = n.prev
+		count++
+	}
+	for count > 0 {
+		n = n.next
+		count--
+	}
+	return n
+}
+
+func mix(n *Node, listLen int) {
+	t := n.prev
+	n.prev.next = n.next
+	n.next.prev = n.prev
+	t = move(t, n.value%(listLen-1))
+	n.prev = t
+	n.next = t.next
+	n.prev.next = n
+	n.next.prev = n
+}
+
+func mixAll(list []*Node) {
+	for _, n := range list {
+		mix(n, len(list))
+	}
+}
+
+func getCoords(first *Node) int {
+	var res int
+	for i, n := 0, first; i < 3; i++ {
+		n = move(n, 1000)
+		res += n.value
+	}
+	return res
+}