캐슬 디펜스-17135번(java)

https://www.acmicpc.net/problem/17135

17135번: 캐슬 디펜스

package a0813;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.StringTokenizer;

public class Main_bj_17135_캐슬디펜스_서울_12반_이서영 {

	static int n, m, d;
	static StringTokenizer st;
	static int num;
	static ArrayList<Pair> enemies = new ArrayList<>();
	static ArrayList<Pair> emptyPos = new ArrayList<>();
	static int max = 0;

	static class Pair {
		int x, y;

		Pair(int x, int y) {
			this.x = x;
			this.y = y;
		}
	}

	public static int simulate(ArrayList<Pair> posList, ArrayList<Pair> tmpEnemies) {

		int death = 0;

		while (!tmpEnemies.isEmpty()) {

			HashSet<Pair> hs = new HashSet<>();
			for (int i = 0; i < posList.size(); i++) {

				int px = posList.get(i).x;
				int py = posList.get(i).y;

				int mindist = Integer.MAX_VALUE;
				int mj = -1;
				int mex = -1;
				int mey = -1;

				for (int j = 0; j < tmpEnemies.size(); j++) {

					int ex = tmpEnemies.get(j).x;
					int ey = tmpEnemies.get(j).y;

					int dist = Math.abs(px - ex) + Math.abs(py - ey);

					if (dist <= d) {
						if (mindist > dist) {
							mj = j;
							mex = ex;
							mey = ey;
							mindist = dist;
						} else if (mindist == dist) {
							if (mey > ey) {
								mj = j;
								mex = ex;
								mey = ey;
							}
						}
					}
				}

				if (mj != -1) {
					hs.add(tmpEnemies.get(mj));
				}

			}

			LinkedList<Pair> ls = new LinkedList<>(hs);

			for (Pair p : ls) {
				death++;
				tmpEnemies.remove(p);
				//hs = new HashSet<>();
				hs.clear();
			}

			for (int t = 0; t < tmpEnemies.size(); t++) {
				if ((tmpEnemies.get(t).x + 1) >= n) {

					tmpEnemies.remove(t);
					t--;
				} else {
					tmpEnemies.get(t).x = tmpEnemies.get(t).x + 1;
				}
			}

		}

		return death;

	}

	// 궁수의 위치를 조합으로 구한다. 
	public static void decidePos(ArrayList<Pair> posList, boolean[] selected, int idx) {

		if (posList.size() == 3) {

			ArrayList<Pair> tmpEnemies = new ArrayList<>();

			for (int i = 0; i < enemies.size(); i++) {
				tmpEnemies.add(new Pair(enemies.get(i).x, enemies.get(i).y));
			} // *주의* Pair도 다시 할당 해주어야함!!!

			max = Math.max(max, simulate(posList, tmpEnemies));

			return;
		}

		for (int i = idx; i < emptyPos.size(); i++) {

			if (!selected[i]) {
				selected[i] = true;
				posList.add(emptyPos.get(i));

				decidePos(posList, selected, i + 1);

				selected[i] = false;
				posList.remove(posList.size() - 1);
			}

		}

	}

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

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		st = new StringTokenizer(br.readLine());
		n = Integer.parseInt(st.nextToken());
		m = Integer.parseInt(st.nextToken());
		d = Integer.parseInt(st.nextToken());

		for (int i = 0; i < n; i++) {
			st = new StringTokenizer(br.readLine());
			for (int j = 0; j < m; j++) {
				num = Integer.parseInt(st.nextToken());
				if (num == 1) {
					enemies.add(new Pair(i, j));
				}
			}
		}

		for (int i = 0; i < m; i++) {
			emptyPos.add(new Pair(n, i));
		}

		decidePos(new ArrayList<>(), new boolean[emptyPos.size()], 0);
		System.out.println(max);

	}

}

- java는 Pair클래스를 만들었으면 꼭 파라미터로 보내주기 전에 새로 초기화를 해주어야한다.