[JAVA] Boj 2636 | 치즈
2021, Feb 18
문제
- [Boj 2636 - 치즈 ]
- 해결방법 : bfs로 푸는 문제 , 문제를 보고 어떻게 bfs를 생각해내지? , 구글링해서 풀 수 있던 문제다 , 공기일경우 큐에 넣고 치즈일경우 녹여주면 된다
나의 풀이
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| package day7; | |
| import java.io.BufferedReader; | |
| import java.io.IOException; | |
| import java.io.InputStreamReader; | |
| import java.util.LinkedList; | |
| import java.util.Queue; | |
| import java.util.StringTokenizer; | |
| public class Boj_2636 { | |
| static class Pos{ | |
| int x,y; | |
| Pos(int x, int y){ | |
| this.x=x; | |
| this.y=y; | |
| } | |
| } | |
| static int R,C; | |
| static int[][] cheese; | |
| static int cheeseCnt; | |
| public static void main(String[] args) throws IOException { | |
| BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); | |
| StringTokenizer st = new StringTokenizer(br.readLine()); | |
| R = Integer.parseInt(st.nextToken()); | |
| C = Integer.parseInt(st.nextToken()); | |
| cheese = new int[R][C]; | |
| for(int i=0;i<R;i++) { | |
| st = new StringTokenizer(br.readLine()); | |
| for(int j=0;j<C;j++) { | |
| cheese[i][j]=Integer.parseInt(st.nextToken()); | |
| if(cheese[i][j]==1) { | |
| cheeseCnt++; | |
| } | |
| } | |
| } | |
| int time=0; | |
| int prevCnt =0; | |
| //치즈가 남아있는 경우 계속 돌아간다 | |
| while(cheeseCnt>0){ | |
| prevCnt = cheeseCnt; //이전치즈 개수 | |
| melting(); | |
| time++; | |
| } | |
| System.out.println(time+"\n"+prevCnt); | |
| } | |
| static int[][]dirs = {{-1,0},{1,0},{0,-1},{0,1}}; | |
| // BFS | |
| private static void melting() { | |
| boolean[][] visited = new boolean[R][C]; | |
| Queue<Pos> que = new LinkedList<>(); | |
| que.offer(new Pos(0,0)); | |
| visited[0][0]=true; | |
| while(!que.isEmpty()) { | |
| Pos tmp = que.poll(); | |
| for(int i=0;i<dirs.length;i++) { | |
| int dx = tmp.x+dirs[i][0]; | |
| int dy = tmp.y+dirs[i][1]; | |
| if(dx<0 || dx>=R || dy<0 || dy>=C || visited[dx][dy]) continue; | |
| // 공기 | |
| if(cheese[dx][dy]==0 ) { | |
| visited[dx][dy]=true; | |
| que.offer(new Pos(dx,dy)); | |
| } | |
| // 접촉치즈 | |
| else { | |
| visited[dx][dy]=true; | |
| cheese[dx][dy]=0; | |
| cheeseCnt--; | |
| } | |
| } | |
| } | |
| } | |
| } |