adventofcode/src/main/java/AoC2016_19.java at main · pareronia/adventofcode · GitHub

History

115 lines (98 loc) · 3.01 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

import java.util.List;

import com.github.pareronia.aoc.solution.Sample;

import com.github.pareronia.aoc.solution.Samples;

import com.github.pareronia.aoc.solution.SolutionBase;

public class AoC2016_19 extends SolutionBase<String, Integer, Integer> {

private AoC2016_19(final boolean debug) {

super(debug);

}

public static AoC2016_19 create() {

return new AoC2016_19(false);

}

public static AoC2016_19 createDebug() {

return new AoC2016_19(true);

}

@Override

protected String parseInput(final List<String> inputs) {

return inputs.get(0);

}

@Override

public Integer solvePart1(final String input) {

final Elves elves = Elves.fromInput(input);

Node curr = elves.head;

while (elves.size > 1) {

final Node loser = curr.next;

elves.remove(loser);

curr = curr.next;

}

return curr.value;

}

@Override

public Integer solvePart2(final String input) {

final Elves elves = Elves.fromInput(input);

Node curr = elves.head;

Node opposite = elves.head;

for (int i = 0; i < elves.size / 2; i++) {

opposite = opposite.next;

}

while (elves.size > 1) {

final Node loser = opposite;

elves.remove(loser);

if (elves.size % 2 == 1) {

opposite = opposite.next;

} else {

opposite = opposite.next.next;

}

curr = curr.next;

}

return curr.value;

}

@Samples({

@Sample(method = "part1", input = TEST, expected = "3"),

@Sample(method = "part2", input = TEST, expected = "2"),

})

public static void main(final String[] args) throws Exception {

AoC2016_19.create().run();

}

private static final String TEST = "5";

private static final class Elves {

private Node head;

private int size;

public Elves() {

this.head = null;

this.size = 0;

}

public static Elves fromInput(final String input) {

final Elves elves = new Elves();

Node node = null;

Node prev = null;

for (int i = 0; i < Integer.parseInt(input); i++) {

node = new Node(i + 1);

if (elves.size == 0) {

elves.head = node;

} else {

node.prev = prev;

prev.next = node;

}

prev = node;

elves.size++;

}

elves.head.prev = node;

node.next = elves.head;

return elves;

}

public void remove(final Node node) {

node.prev.next = node.next;

node.next.prev = node.prev;

this.size--;

}

private static class Node {

public int value;

public Node next;

public Node prev;

public Node(final int value) {

this.value = value;

}

adventofcode/src/main/java/AoC2016_19.java at main · pareronia/adventofcode · GitHub

Expand file tree

Breadcrumbs

AoC2016_19.java

Latest commit

History

Breadcrumbs

AoC2016_19.java

File metadata and controls