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[AOC-12] Day 12 code. Typical navigation problem.
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‎2020/src/main/java/com/nbrevu/advent2020/Advent12_1.java

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package com.nbrevu.advent2020;
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import java.io.IOException;
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import java.net.URL;
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import java.util.EnumMap;
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import java.util.Map;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import com.google.common.base.Charsets;
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import com.google.common.io.Resources;
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public class Advent12_1 {
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private final static String IN_FILE="Advent12.txt";
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private final static Pattern LINE_PATTERN=Pattern.compile("^([NSEWLRF])(\\d+)");
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private static enum Direction {
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EAST {
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@Override
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public void moveForward(Position p,int amount) {
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p.x+=amount;
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}
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},
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NORTH {
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@Override
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public void moveForward(Position p,int amount) {
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p.y+=amount;
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}
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},
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WEST {
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@Override
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public void moveForward(Position p,int amount) {
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p.x-=amount;
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}
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},
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SOUTH {
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@Override
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public void moveForward(Position p,int amount) {
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p.y-=amount;
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}
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};
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public abstract void moveForward(Position p,int amount);
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private final static Map<Direction,Direction> LEFT_ROTATIONS=createLeftRotations();
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private final static Map<Direction,Direction> RIGHT_ROTATIONS=createRightRotations();
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private static Map<Direction,Direction> createLeftRotations() {
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Map<Direction,Direction> result=new EnumMap<>(Direction.class);
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result.put(EAST,NORTH);
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result.put(NORTH,WEST);
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result.put(WEST,SOUTH);
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result.put(SOUTH,EAST);
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return result;
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}
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private static Map<Direction,Direction> createRightRotations() {
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Map<Direction,Direction> result=new EnumMap<>(Direction.class);
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result.put(EAST,SOUTH);
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result.put(NORTH,EAST);
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result.put(WEST,NORTH);
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result.put(SOUTH,WEST);
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return result;
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}
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public Direction rotateLeft() {
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return LEFT_ROTATIONS.get(this);
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}
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public Direction rotateRight() {
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return RIGHT_ROTATIONS.get(this);
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}
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}
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private static class Position {
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public Direction dir;
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public int x;
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public int y;
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public Position() {
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dir=Direction.EAST;
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x=0;
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y=0;
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}
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}
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private static enum Action {
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N {
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@Override
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public void act(Position pos,int amount) {
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Direction.NORTH.moveForward(pos,amount);
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}
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},
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S {
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@Override
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public void act(Position pos,int amount) {
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Direction.SOUTH.moveForward(pos,amount);
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}
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},
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E {
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@Override
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public void act(Position pos,int amount) {
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Direction.EAST.moveForward(pos,amount);
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}
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},
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W {
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@Override
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public void act(Position pos,int amount) {
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Direction.WEST.moveForward(pos,amount);
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}
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},
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L {
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@Override
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public void act(Position pos,int amount) {
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int realAmount=amount/90;
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for (int i=0;i<realAmount;++i) pos.dir=pos.dir.rotateLeft();
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}
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},
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R {
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@Override
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public void act(Position pos,int amount) {
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int realAmount=amount/90;
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for (int i=0;i<realAmount;++i) pos.dir=pos.dir.rotateRight();
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}
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},
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F {
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@Override
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public void act(Position pos,int amount) {
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pos.dir.moveForward(pos,amount);
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}
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};
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public abstract void act(Position pos,int amount);
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}
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public static void main(String[] args) throws IOException {
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URL file=Resources.getResource(IN_FILE);
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Position p=new Position();
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for (String line:Resources.readLines(file,Charsets.UTF_8)) {
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Matcher matcher=LINE_PATTERN.matcher(line);
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if (matcher.matches()) {
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Action a=Action.valueOf(matcher.group(1));
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int amount=Integer.parseInt(matcher.group(2));
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a.act(p,amount);
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}
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}
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int result=Math.abs(p.x)+Math.abs(p.y);
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System.out.println(result);
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}
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}

‎2020/src/main/java/com/nbrevu/advent2020/Advent12_2.java

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package com.nbrevu.advent2020;
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import java.io.IOException;
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import java.net.URL;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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import com.google.common.base.Charsets;
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import com.google.common.io.Resources;
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public class Advent12_2 {
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private final static String IN_FILE="Advent12.txt";
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private final static Pattern LINE_PATTERN=Pattern.compile("^([NSEWLRF])(\\d+)");
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private static class Waypoint {
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public int x;
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public int y;
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public Waypoint() {
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this.x=0;
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this.y=0;
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}
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public void forward(Position p,int amount) {
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p.x+=x*amount;
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p.y+=y*amount;
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}
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public void rotateLeft() {
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int newX=-y;
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int newY=x;
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x=newX;
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y=newY;
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}
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public void rotateRight() {
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int newX=y;
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int newY=-x;
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x=newX;
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y=newY;
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}
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}
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private static class Position {
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public int x;
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public int y;
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public Position() {
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x=0;
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y=0;
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}
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}
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private static enum Action {
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N {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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wp.y+=amount;
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}
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},
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S {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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wp.y-=amount;
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}
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},
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E {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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wp.x+=amount;
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}
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},
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W {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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wp.x-=amount;
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}
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},
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L {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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int realAmount=amount/90;
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for (int i=0;i<realAmount;++i) wp.rotateLeft();
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}
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},
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R {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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int realAmount=amount/90;
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for (int i=0;i<realAmount;++i) wp.rotateRight();
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}
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},
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F {
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@Override
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public void act(Position pos,Waypoint wp,int amount) {
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wp.forward(pos,amount);
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}
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};
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public abstract void act(Position pos,Waypoint wp,int amount);
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}
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public static void main(String[] args) throws IOException {
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URL file=Resources.getResource(IN_FILE);
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Position p=new Position();
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Waypoint wp=new Waypoint();
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wp.x=10;
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wp.y=1;
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for (String line:Resources.readLines(file,Charsets.UTF_8)) {
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Matcher matcher=LINE_PATTERN.matcher(line);
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if (matcher.matches()) {
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Action a=Action.valueOf(matcher.group(1));
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int amount=Integer.parseInt(matcher.group(2));
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a.act(p,wp,amount);
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}
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}
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int result=Math.abs(p.x)+Math.abs(p.y);
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System.out.println(result);
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}
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}

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