[BOJ] 백준 16234 인구 이동

[문제]

https://www.acmicpc.net/problem/16234

 

 

[소스 코드]

import java.io.*;
import java.util.*;

public class Main {
	static int n,l,r;
	static boolean move;
	static int[][] map;
	static boolean[][] visit;
	static List<int[]> list;
	static int[] dr = {-1,0,1,0};
	static int[] dc = {0,1,0,-1};
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		n = Integer.parseInt(st.nextToken());
		l = Integer.parseInt(st.nextToken());
		r = Integer.parseInt(st.nextToken());
		map = new int[n][n];
		for(int i=0;i<n;i++) {
			st = new StringTokenizer(br.readLine());
			for(int j=0;j<n;j++) {
				map[i][j] = Integer.parseInt(st.nextToken());
			}
		}
		int day = 0;
		while(true) {
			visit = new boolean[n][n];
			move = false;
			for(int i=0;i<n;i++) {
				for(int j=0;j<n;j++) {
					if(!visit[i][j]) {
						bfs(i,j);
					}
				}
			}
			if(!move) break;
			day++;
		}
		System.out.println(day);
	}
	private static void bfs(int i,int j) {
		Queue<int[]> q = new LinkedList<>();
		list = new ArrayList<>();
		
		q.offer(new int[] {i,j});
		int sum = 0;
		
		while(!q.isEmpty()) {
			int[] curr = q.poll();
			for(int d=0;d<4;d++) {
				int nr = curr[0] + dr[d];
				int nc = curr[1] + dc[d];
				if(nr<0 || nr>=n || nc<0 || nc>=n || visit[nr][nc]) continue;
				int diff = Math.abs(map[curr[0]][curr[1]] - map[nr][nc]);
				if(diff>=l && diff<=r) {
					sum += map[nr][nc];
					visit[nr][nc] = true;
					q.offer(new int[] {nr,nc});
					list.add(new int[] {nr,nc});
				}
			}
		}
		if(list.size()>0) 
			divide(sum);
	}
	private static void divide(int sum) {
		move = true;
		int avg = sum / list.size();
		for(int[] p : list) {
			map[p[0]][p[1]] = avg;
		}
	}
}