백준 16928번) 뱀과 사다리 게임 (다시풀어보기)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {
	static HashMap<Integer, Integer> map = new HashMap<>();
	static class Location {
		int n, distance;

		public Location(int n, int distance) {
			this.n = n;
			this.distance = distance;
		}
	}
	public static int BFS(int start_point, int last_point) {
		boolean[] visited = new boolean[101];
		Queue<Location> will_visit = new LinkedList<Location>();
		Location start = new Location(start_point, 0);
		will_visit.add(start);
		while (will_visit.size() > 0) {
			Location current_point = will_visit.remove();

			if (current_point.n == last_point)
				return current_point.distance;
			if (current_point.n < 1 || current_point.n > 100)
				continue;
			if (visited[current_point.n])
				continue;
			visited[current_point.n] = true;

			if(map.containsKey(current_point.n))
			{
				will_visit.add(new Location(map.get(current_point.n), current_point.distance));
			}
			else
			{
				will_visit.add(new Location(current_point.n + 1, current_point.distance + 1));
				will_visit.add(new Location(current_point.n + 2, current_point.distance + 1));
				will_visit.add(new Location(current_point.n + 3, current_point.distance + 1));
				will_visit.add(new Location(current_point.n + 4, current_point.distance + 1));
				will_visit.add(new Location(current_point.n + 5, current_point.distance + 1));
				will_visit.add(new Location(current_point.n + 6, current_point.distance + 1));
			}

		}
		return -1;
	}


	static void start_game()
	{
		System.out.println(BFS(1,100));
	}

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer stringTokenizer = new StringTokenizer(reader.readLine());
		int N = Integer.parseInt(stringTokenizer.nextToken());
		int M = Integer.parseInt(stringTokenizer.nextToken());

		for(int i=0;i<N;i++) {
            String [] XY = reader.readLine().split(" ");
            int x = Integer.parseInt(XY[0]);
            int y = Integer.parseInt(XY[1]);
            map.put(x, y);
        }
        for(int i=0 ; i<M ; i++) {
            String [] UV = reader.readLine().split(" ");
            int u = Integer.parseInt(UV[0]);
            int v = Integer.parseInt(UV[1]);
            map.put(u, v);
        }
		start_game();
		reader.close();

	}
}

-----------수정-----------

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {
	static HashMap<Integer, Integer> map = new HashMap<>();
	static int[] board = new int[101];

	static class Location {
		int n, distance;

		public Location(int n, int distance) {
			this.n = n;
			this.distance = distance;
		}
	}

	public static int BFS(int start_point, int last_point) {
		boolean[] visited = new boolean[101];
		Queue<Location> will_visit = new LinkedList<Location>();
		Location start = new Location(start_point, 0);
		will_visit.add(start);
		while (will_visit.size() > 0) {
			Location current_point = will_visit.poll();
			visited[current_point.n] = true;
			if (current_point.n == last_point)
				return current_point.distance;

			for (int i = 1; i <= 6; i++) {
				int nnow = current_point.n+i;
				if (100 < nnow)
					continue;
				if (visited[nnow])
					continue;
				visited[nnow] = true;
				Location next_point = new Location(nnow, current_point.distance + 1);
				if (map.containsKey(next_point.n)) {
					int ntemp = map.get(next_point.n);
					if (!visited[ntemp]) {
						visited[ntemp] = true;
						will_visit.add(new Location(ntemp, current_point.distance + 1));
					}

				} else {
					will_visit.add(next_point);
				}

			}
		}
		return -1;
	}

	static void start_game() {
		System.out.println(BFS(1, 100));
	}

	public static void main(String[] args) throws NumberFormatException, IOException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer stringTokenizer = new StringTokenizer(reader.readLine());
		int N = Integer.parseInt(stringTokenizer.nextToken());
		int M = Integer.parseInt(stringTokenizer.nextToken());

		for (int i = 0; i < N; i++) {
			String[] XY = reader.readLine().split(" ");
			int x = Integer.parseInt(XY[0]);
			int y = Integer.parseInt(XY[1]);
			map.put(x, y);
		}
		for (int i = 0; i < M; i++) {
			String[] UV = reader.readLine().split(" ");
			int u = Integer.parseInt(UV[0]);
			int v = Integer.parseInt(UV[1]);
			map.put(u, v);
		}
		start_game();
		reader.close();

	}
}