adventofcode/2016/day19/main.go

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package main
import (
"fmt"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
// pt1 input: 3014387
func main() {
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partOne := h.ArgIsSet("-1")
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num := 3014387
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if h.ArgIsSet("-test") {
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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
}