백준 19236 청소년 상어 (Java)

* 해당 포스팅은 구버전

* alwaysbemoon.tistory.com/228 

[백준 19236, Java] 청소년 상어

---

1. 아ㅏㅏ아아아 객체객체객체객체 .... 어렵다 객체

 

1) 객체를 매개변수로 넘길때는 반드시 복사

2) 객체 값을 변경시키고서 매개변수로 넘기면 다시 돌아왔을 때 초기값으로 함수수행하지 않고 변경된 값으로 수행 (이거때문에 하루 날림 ㅜㅜ)

 - currentShark.x 를 변경하면 안됨

		for(int d = 1;d<=4; d++) {
			int moveSharkX = currentShark.x + dx[currentShark.direction]*d; 
			int moveSharkY = currentShark.y + dy[currentShark.direction]*d;
			
			
			if(moveSharkX<0 || moveSharkX>= 4 ||moveSharkY<0 ||moveSharkY>=4) {
				return;
			}
			else{
				if(tempMap[moveSharkX][moveSharkY] == BLANK) {
					continue;
				}
				else {
					tempMap[currentShark.x][currentShark.y] =0;
					System.out.println("("+currentShark.x+","+currentShark.y+")=0");
					currentShark.x = moveSharkX;
					currentShark.y= moveSharkY;
					
					
					eatFish(currentShark,tempMap,tempFishList);	
				}
			}
		}

3) 객체배열은 꼭 초기화를 해야하고 null이 있으면 안돼요....그리고 객체를 복사할 때는 깊은복사를 해야합니다.

이거 자바책에서 그렇게 밑줄친건데 ㅜㅜ

	public static void copyList(Fish[]source, Fish[] dest) {
		for(int i=0;i<source.length;i++) {
			dest[i] = source[i];
		}
	}

위가 아니라

아래

	public static void copyList(Fish[]source, Fish[] dest) {
		for(int i=1;i<source.length;i++) {
			if(source[i]!=null) {
				dest[i] = new Fish();
				dest[i].x = source[i].x;
				dest[i].y = source[i].y;
				dest[i].number = source[i].number;
				dest[i].direction =source[i].direction;
			}
			
		}
	}

 

 

코드

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;



class Fish{
	int number;
	int x;
	int y;
	int direction;
	
	Fish(int number, int x , int y, int direction){
		this.number = number;
		this.x =x ;
		this.y =y;
		this.direction = direction;
	}
	Fish(){
		
	}
	@Override
	public String toString() {
		return "number:"+number+"("+x+","+y+"),d :"+direction;
	}
	
}


public class Main{
	public static int[][] map;
	
	
	public static int SHARK = -1;
	public static int BLANK = 0;
	
	public static int[] dx = {-1,-1, 0, 1,1,1, 0,-1};
	public static int[] dy = { 0,-1,-1,-1,0,1, 1, 1};
	
	public static int maxFishSum = 0;
	
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		StringTokenizer st;
		
		map = new int[4][4];
		Fish[] fishList = new Fish[17];
		
		
		for(int r=0;r<4;r++) {
			int c =0;
			int fishNumber = 0;
			int fishX = 0;
			int fishY = 0;
			int fishDirection = 0;
			
			
			st = new StringTokenizer(br.readLine(), " ");
			
			fishNumber = Integer.parseInt(st.nextToken());
			fishDirection = Integer.parseInt(st.nextToken())-1;
			fishX = r;
			fishY = c;
			
			fishList[fishNumber] = new Fish(fishNumber ,fishX, fishY,fishDirection);
			map[fishX][fishY] =fishNumber;
			c++;
			
			fishNumber = Integer.parseInt(st.nextToken());
			fishDirection = Integer.parseInt(st.nextToken())-1;
			fishX = r;
			fishY = c;
			
			fishList[fishNumber] = new Fish(fishNumber ,fishX, fishY,fishDirection);
			map[fishX][fishY] =fishNumber;
			c++;
			
			fishNumber = Integer.parseInt(st.nextToken());
			fishDirection = Integer.parseInt(st.nextToken())-1;
			fishX = r;
			fishY = c;
			
			fishList[fishNumber] = new Fish(fishNumber ,fishX, fishY,fishDirection);
			map[fishX][fishY] =fishNumber;
			c++;
			
			fishNumber = Integer.parseInt(st.nextToken());
			fishDirection = Integer.parseInt(st.nextToken())-1;
			fishX = r;
			fishY = c;
			
			fishList[fishNumber] = new Fish(fishNumber ,fishX, fishY,fishDirection);
			map[fishX][fishY] =fishNumber;
			c++;
		}
		
	
		eatFish(0, 0 ,0,0,map,fishList);
		bw.write(String.valueOf(maxFishSum));
		bw.flush();
	}
	
	public static void eatFish(int sx, int sy, int sd, int sum, int[][] map, Fish[] fishList) {
		int[][] tempMap = new int[4][4];
		copyMap(map,tempMap);
		
		Fish[] tempFishList = new Fish[17];
		copyList(fishList,tempFishList);
		
		
		int eatFishNumber = tempMap[sx][sy];
		Fish eatFish = tempFishList[eatFishNumber];
		
		//상어상태 업데이트
		sd = eatFish.direction;
		sum += eatFishNumber;
		maxFishSum = Math.max(maxFishSum, sum);
		
		//물고기리스트 업데이트 
		tempFishList[eatFishNumber] = null;
		
		//map업데이트
		tempMap[sx][sy] = SHARK;
		
		
		
		/* 물고기 이동 */
		for(int number = 1; number<tempFishList.length;number++) {
			if(tempFishList[number]!=null) {
				//이동할 물고기
				Fish moveFish = tempFishList[number];
				
				//이동 탐색
				for(int d = moveFish.direction; d<moveFish.direction+8; d++) {
					d = d%8;
					int mx = moveFish.x + dx[d];
					int my = moveFish.y +dy[d];
					
					//경계 밖
					if(mx<0 || mx>=4 || my<0 || my>=4) {
						continue;
					}
					//경계 안
					else {
						if(tempMap[mx][my] == SHARK) {
							continue;
						}
						else if(tempMap[mx][my] == BLANK) {
							//빈칸으로 물고기 이동(물고기의 좌표 변경)
							tempMap[moveFish.x][moveFish.y] =BLANK;
							
							moveFish.x = mx;
							moveFish.y = my;
							moveFish.direction =d;
							
							tempMap[mx][my] = number;
							tempFishList[number] = moveFish;
							
							break;
						}
						else {
							//물고기 자리 변경 
							int changeFishNumber = tempMap[mx][my];
							Fish changeFish = tempFishList[changeFishNumber];
							
							//map 상태 업데이트
							tempMap[moveFish.x][moveFish.y] = changeFishNumber;
							tempMap[changeFish.x][changeFish.y] = number;
							
							
							//물고기 상태 업데이트
							int currentFishX = moveFish.x;
							int currentFishY = moveFish.y;
							int currentFishD = d;
							
							int changeFishX = changeFish.x;
							int changeFishY = changeFish.y;
							
							
							tempFishList[number].x =  changeFishX;
							tempFishList[number].y = changeFishY;
							tempFishList[number].direction =currentFishD;
							
							tempFishList[changeFishNumber].x = currentFishX;
							tempFishList[changeFishNumber].y = currentFishY;
							break;
						}
					}
				}
				
			}
		}
		
		/* 상어이동 이동 */
		
		for(int d = 1;d<=4; d++) {
			int moveSharkX = sx + dx[sd]*d; 
			int moveSharkY = sy + dy[sd]*d;
			
			if(moveSharkX<0 || moveSharkX>= 4 ||moveSharkY<0 ||moveSharkY>=4) {
				break;
			}
			else{
				if(tempMap[moveSharkX][moveSharkY] == BLANK) {
					continue;
				}
				else {
					tempMap[sx][sy] =0;
					eatFish(moveSharkX,moveSharkY,sd,sum,tempMap,tempFishList);	
				}
			}
		}
	}
	
	
	public static void copyList(Fish[]source, Fish[] dest) {
		for(int i=1;i<source.length;i++) {
			if(source[i]!=null) {
				dest[i] = new Fish();
				dest[i].x = source[i].x;
				dest[i].y = source[i].y;
				dest[i].number = source[i].number;
				dest[i].direction =source[i].direction;
			}
			
		}
	}
	public static void copyMap(int[][] source, int[][] dest) {
		for(int r=0;r<4;r++) {
			for(int c=0;c<4;c++)
				dest[r][c] = source[r][c];
		}
	}
	
	public static void printMap(int[][] m) {
		for(int r=0;r<4;r++) {
			for(int c=0;c<4;c++) {
				System.out.print(m[r][c]+" ");
			}
			System.out.println();
		}
	}
}