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Day11.java
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Day11.java
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import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ArrayBlockingQueue;
public class Day112 {
private static final byte ZERO = (byte) 0;
private static final byte FLOOR = (byte) 8;
private static final byte FOURTH_FLOOR = FLOOR * 3;
static class Point {
int level;
int generators;
int microchips;
byte n;
int steps;
// List<Long> prev = new ArrayList<>();
Point() {
}
Point(int level, int generators, int microchips, byte n, int steps) {
this.level = level;
this.generators = generators;
this.microchips = microchips;
this.n = n;
this.steps = steps;
}
boolean getNext(Point next, int newLevel, byte chips, byte rtgs) {
// valid floor, chips and generators
if (newLevel > FOURTH_FLOOR || newLevel < 0
|| (microchips >> level & chips) != chips || (generators >> level & rtgs) != rtgs
// nothing below, no point in taking it further down
|| newLevel < level && ((generators >> level) | (microchips >> level)) == 0) {
return false;
}
byte genNL = (byte) (generators >> newLevel & n | rtgs);
byte micNL = (byte) (microchips >> newLevel & n | chips);
if (genNL != 0 && (genNL & micNL) == 0) {
// none of the RTGs have corresponding microchips, you are dead
return false;
}
if (micNL != 0 && genNL != 0 && (micNL & genNL) != micNL) {
// there are microchips exposed to incompatible RTGs and are fried
return false;
}
byte genCL = (byte) (generators >> level & n & ~rtgs);
byte micCL = (byte) (microchips >> level & n & ~chips);
if (micCL != 0 && genCL != 0 && (micCL & genCL) != micCL) {
// there are microchips exposed to incompatible RTGs
return false;
}
int floorMask = ~(n << level | n << newLevel);
int newGenerators = genNL << newLevel | genCL << level | floorMask & generators;
int newMicrochips = micNL << newLevel | micCL << level | floorMask & microchips;
next.level = newLevel;
next.generators = newGenerators;
next.microchips = newMicrochips;
next.n = n;
next.steps = steps + 1;
// next.prev.clear();
// next.prev.addAll(prev);
// next.prev.add((long) generators << 32 | microchips);
return true;
}
@Override
public String toString() {
String genbin = Integer.toBinaryString(generators);
String micbin = Integer.toBinaryString(microchips);
return level / FLOOR + "[" + genbin + "][" + micbin + "]";
}
@Override
public int hashCode() {
int result = 1;
result = 31 * result + level / FLOOR;
result = 31 * result + generators;
result = 31 * result + microchips;
return result;
}
}
private static int part1(byte[] elements, String[] elementStrings, int generators, int microchips) {
int all = 0;
for (byte e : elements) {
all |= e;
}
Queue<Point> points = new ArrayBlockingQueue<>(500000);
Point start = new Point(0, generators, microchips, (byte) all, 0);
points.add(start);
Set<Integer> visited = new HashSet<>();
visited.add(start.hashCode());
all = all << FOURTH_FLOOR;
while (!points.isEmpty()) {
Point p = points.poll();
// System.out.println(printPoint(elements, elementStrings, p));
if (p.generators == all && p.microchips == all) {
// printSteps(elements, elementStrings, p.prev);
return p.steps;
}
for (int i = 0; i < elements.length; i++) {
Point next = new Point();
// take just this chip
next = addNext(p, next, elements[i], ZERO, visited, points);
// take this chip and its gen
next = addNext(p, next, elements[i], elements[i], visited, points);
// take just this generator
next = addNext(p, next, ZERO, elements[i], visited, points);
for (int j = i + 1; j < elements.length; j++) {
// take this chip and another chip
next = addNext(p, next, (byte) (elements[i] | elements[j]), ZERO, visited, points);
// take this gen and another gen
next = addNext(p, next, ZERO, (byte) (elements[i] | elements[j]), visited, points);
// take this chip and another gen
next = addNext(p, next, elements[i], elements[j], visited, points);
// take this gen and another chip
next = addNext(p, next, elements[j], elements[i], visited, points);
}
}
}
return -1;
}
private static Point addNext(Point current, Point next, byte chips, byte rtgs, Set<Integer> visited,
Queue<Point> points) {
if (current.getNext(next, current.level - FLOOR, chips, rtgs) && visited.add(next.hashCode())) {
points.add(next);
next = new Point();
}
if (current.getNext(next, current.level + FLOOR, chips, rtgs) && visited.add(next.hashCode())) {
points.add(next);
next = new Point();
}
return next;
}
private static String printPoint(byte[] elements, String[] elementStrings, Point p) {
StringBuilder b = new StringBuilder();
for (int i = 3; i >= 0; i--) {
b.append('F').append(i + 1).append(' ');
b.append(p.level == i ? 'E' : '.');
b.append(" ");
for (int i1 = 0; i1 < elements.length; i1++) {
byte e = elements[i1];
if ((p.generators >> FLOOR * i & e) == e) {
b.append(elementStrings[i1]).append("G ");
}
else {
b.append(". ");
}
if ((p.microchips >> FLOOR * i & e) == e) {
b.append(elementStrings[i1]).append("M ");
}
else {
b.append(". ");
}
}
b.append('\n');
}
return b.toString();
}
private static void printSteps(byte[] elements, String[] elementStrings, List<Long> steps) {
StringBuilder b = new StringBuilder();
for (long step : steps) {
b.setLength(0);
int generators = (int) (step >> 32);
int microchips = (int) step;
for (int i = FOURTH_FLOOR; i >= 0; i -= FLOOR) {
b.append('F').append(i / FLOOR + 1).append(' ');
// b.append(p.level == i ? 'E' : '.');
b.append(". ");
for (int i1 = 0; i1 < elements.length; i1++) {
byte e = elements[i1];
if ((generators >> i & e) == e) {
b.append(elementStrings[i1]).append("G ");
}
else {
b.append(". ");
}
if ((microchips >> i & e) == e) {
b.append(elementStrings[i1]).append("M ");
}
else {
b.append(". ");
}
}
b.append('\n');
}
System.out.println(b.toString());
}
}
public static void main(String[] args) {
System.out
.println(part1(new byte[] { 0b1, 0b10 }, new String[] { "H ", "L " }, 0b0_10_00000001_00000000, 0b0_0_0_11));
/**
* The first floor contains a PmG and a PmM <br/>
* The second floor contains a CoG, a CmG, a RuG, and a PuG. <br/>
* The third floor contains a CoM, a CmM, a RuM, and a PuM. <br/>
* The fourth floor contains nothing relevant. <br/>
*/
// Promethium
final byte Pm = 0x01;
// Cobalt
final byte Co = 0x02;
// Curium
final byte Cm = 0x04;
// Ruthenium
final byte Ru = 0x08;
// Plutonium
final byte Pu = 0x10;
byte[] elements = { Pm, Co, Cm, Ru, Pu };
String[] elementStrings = { "Pm", "Co", "Cm", "Ru", "Pu" };
System.out.println(part1(elements, elementStrings, 0b0_0_11110_00000001, 0b0_11110_00000000_00000001));
// Elerium
final byte El = 0x20;
// Dilithium
final byte Di = 0x40;
elements = new byte[] { Pm, Co, Cm, Ru, Pu, El, Di };
elementStrings = new String[] { "Pm", "Co", "Cm", "Ru", "Pu", "El", "Di" };
long start = System.currentTimeMillis();
System.out.println(part1(elements, elementStrings, 0b0_0_11110_01100001,
0b0_11110_00000000_01100001));
System.out.println(System.currentTimeMillis() - start);
}
}