Day 19 Complete

2016/day19/main.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"fmt"
+
+	"../../"
+)
+
+// pt1 input: 3014387
+func main() {
+	partOne := aoc.ArgIsSet("-1")
+	num := 3014387
+	if aoc.ArgIsSet("-test") {
+		num = 5 // Example
+	}
+	firstElf := CreateElf(1)
+	t := CreateElf(2)
+	firstElf.setLeft(t)
+	t.setRight(firstElf)
+	fmt.Println("Generating Elves...")
+	for i := 3; i <= num; i++ {
+		nextElf := CreateElf(i)
+		nextElf.setRight(t)
+		t.setLeft(nextElf)
+		t = nextElf
+	}
+	t.setLeft(firstElf)
+	firstElf.setRight(t)
+
+	fmt.Println(num, "Elves Generated.")
+	fmt.Println("Initiating Greed Injection...")
+
+	t = firstElf
+	if !partOne {
+		t = GetElfAcrossCircle(t, num)
+	}
+	for t.getLeft() != t {
+		if partOne {
+			// Remove the elf to the left
+			t = t.getLeft()
+			t = t.remove()
+			num--
+		} else {
+			// Remove the current elf, the next elf to be removed is the one to the left
+			// (remove() returns a pointer to the elf to it's left)
+			t = t.remove()
+			if num%2 == 1 {
+				// Unless we have an odd number of elves, then we skip this one
+				t = t.getLeft()
+			}
+			num--
+		}
+	}
+	fmt.Println("The lucky elf is elf #", t.getId())
+}
+
+func GetElfAcrossCircle(e *Elf, num int) *Elf {
+	retElf := e
+	for i := 0; i < num/2; i++ {
+		retElf = retElf.getLeft()
+	}
+	return retElf
+}
+
+type Elf struct {
+	id      int
+	out     bool
+	toRight *Elf
+	toLeft  *Elf
+}
+
+// To keep the game running smoothly, an elf is required to
+// let the gamemaster know who the elf to their left is when they
+// are eliminated
+func (e *Elf) remove() *Elf {
+	e.getLeft().setRight(e.getRight())
+	e.getRight().setLeft(e.getLeft())
+	return e.getLeft()
+}
+
+func (e *Elf) getId() int {
+	return e.id
+}
+
+func (e *Elf) getRight() *Elf {
+	return e.toRight
+}
+
+func (e *Elf) setRight(r *Elf) {
+	e.toRight = r
+}
+
+func (e *Elf) getLeft() *Elf {
+	return e.toLeft
+}
+
+func (e *Elf) setLeft(l *Elf) {
+	e.toLeft = l
+}
+
+func CreateElf(id int) *Elf {
+	r := new(Elf)
+	r.id = id
+	return r
+}