나선형배열 문제

README.md

문제

풀이

• http://xper.org/wiki/seminar/SpiralArray
• 정상혁의 Java 8 : https://gist.github.com/benelog/e58577dc57b6641cb104#file-matrix-java
• 오현석님의 Scala
  • http://www.enshahar.me/2014/07/blog-post.html
  • http://www.enshahar.me/2014/07/2_12.html

Matrix.java

package problems;

import static java.util.Arrays.*;

import java.util.Collections;
import java.util.List;
import java.util.Scanner;
import java.util.function.Consumer;

/**
 * Java8 이용, for/if문 없이 구현
 *
 */
public class Matrix {
	static class Position {
		int x;
		int y;
		
		public Position(int x, int y) {
			this.x = x;
			this.y = y;
		}
		
		public boolean isIn(int width, int height) {
		    return ((x >= 0) && (x<width) && (y >=0) && (y<height));  
		}
	}
	
	enum Direction {
		RIGHT(pos -> pos.x++),
		DOWN (pos -> pos.y--),
		LEFT (pos -> pos.x--),
		UP (pos -> pos.y++);		
		static {
			RIGHT.next = DOWN;
			DOWN.next = LEFT;
			LEFT.next = UP;
			UP.next = RIGHT;		
		}
		
		private Direction next;
		private Consumer<Position> mover;
		
		private Direction (Consumer<Position> mover) {
			this.mover = mover;
		}
	
		public void move(Position position) {
			mover.accept(position);
		}

		public Direction getNext() {
			return next;
		}
	}
	private static final int UNREACHED = -1;
	    
	private int height = 0;    
	private int width = 0;
	private int[][] space;
    
	public Matrix(int height, int width){
		this.height = height;
		this.width = width;
		space = new int[height][width];
		stream(space).forEach(row -> fill(row, UNREACHED));
		locate();
	}

	public void print(){
		List<int[]> rows = asList(space);
		Collections.reverse(rows);
		rows.forEach(row ->  {
				stream(row).forEach(n -> System.out.print(n + "\t"));
				System.out.println();
			}
		);
	}
    
	private void locate() {
	    Position pos = new Position(0, height-1); // start Position
	    space[pos.y][pos.x] = 0;
	    Direction direction = Direction.RIGHT;
	    while(move(pos ,direction)) direction = direction.getNext();
	 }
    
	private boolean move(Position pos, Direction direction){
		int step = space[pos.y][pos.x];
		boolean moved = false;
		while(isMovable(pos, direction)) {
			direction.move(pos);
			space[pos.y][pos.x]= ++step;
			moved = true;
		}
		return moved;
	}
	
	private boolean isMovable(Position pos, Direction direction){
		Position nextPos = new Position(pos.x, pos.y);
		direction.move(nextPos);
		return (nextPos.isIn(width, height)) && (space[nextPos.y][nextPos.x] == UNREACHED);
	}
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int row = sc.nextInt();
		int col = sc.nextInt();
		sc.close();
		new Matrix(row,col).print();
	}
}