[백준] 3190 - 뱀

3190번: 뱀

• 1차 코드

  package review;
  
  import java.io.BufferedReader;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.*;
  
  public class ex_3190 {
      static boolean flag;
      static int N,K,L;
      static int[][]board;
      static char dir='R';
      static Deque<Node> q;
      private static class Node{
          int x;
          int y;
          public Node(int x, int y){
              this.x=x;
              this.y=y;
          }
      }
      public static void main(String[] args) throws IOException {
          System.setIn(new FileInputStream("code/src/input/3190.txt"));
          BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
          N = Integer.parseInt(br.readLine());
          K = Integer.parseInt(br.readLine());
          board=new int[N][N];
          board[0][0]=2;
          flag=true;
          int index=1;
          q=new ArrayDeque<>();
          q.addFirst(new Node(0,0));
          for(int i=0;i<K;i++){
              StringTokenizer st = new StringTokenizer(br.readLine());
              int x = Integer.parseInt(st.nextToken());
              int y = Integer.parseInt(st.nextToken());
              board[x-1][y-1]=1;
          }
  
          L = Integer.parseInt(br.readLine());
          char[]turn=new char[10000];
          Arrays.fill(turn,'N');
  
          for(int i=0;i<L;i++){
              StringTokenizer st = new StringTokenizer(br.readLine());
              int X = Integer.parseInt(st.nextToken());
              char C = st.nextToken().charAt(0);
              turn[X]=C;
          }
  
          while(flag){
              move();
              if(turn[index]!='N'){
                  dir=turn[index];
              }
              index++;
          }
          System.out.println(index-1);
      }static void move(){
          Node head=q.peekLast();
          Node tail=q.peekFirst();
          boolean f=false;
          switch(dir){
              case 'U':
                  if(check(head.x-1,head.y)){
                      q.peekLast().x--;
                      f=true;
                  }
                  break;
              case 'D':
                  if(check(head.x+1,head.y)){
                      q.peekLast().x++;
                      f=true;
                  }
                  break;
              case 'L':
                  if(check(head.x,head.y-1)){
                      q.peekLast().y--;
                      f=true;
                  }
                  break;
              case 'R':
                  if(check(head.x,head.y+1)){
                      q.peekLast().y++;
                      f=true;
                  }
                  break;
          }
          if(flag && f){
              board[head.x][head.y]=2;
              q.addLast(new Node(head.x,head.y));
              if(q.size()>1 && board[head.x][head.y]!=1){
                  board[tail.x][tail.y]=0;
                  q.poll();
              }
          }
      }static boolean check(int x, int y){
          if(x<0||y<0||x>=N||y>=N|| board[x][y]==2) {
              flag=false;
              return false;
          }
          else return true;
      }
  }

• 정답 코드

  package review;
  
  import java.io.BufferedReader;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.*;
  
  public class ex_3190 {
      static boolean flag;
      static int N,K,L,pos;
      static int[][]board;
      static char dir='R';
      static Deque<Node> q;
      static int[] dx = { 0, 1, 0,-1};
      static int[] dy = {1, 0, -1,0};
      private static class Node{
          int x;
          int y;
          public Node(int x, int y){
              this.x=x;
              this.y=y;
          }
  
          @Override
          public String toString() {
              return "Node{" +
                      "x=" + x +
                      ", y=" + y +
                      '}';
          }
      }
      public static void main(String[] args) throws IOException {
          System.setIn(new FileInputStream("code/src/input/3190.txt"));
          BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
          N = Integer.parseInt(br.readLine());
          K = Integer.parseInt(br.readLine());
          board=new int[N][N];
          board[0][0]=2;
          flag=true;
          int index=1; pos=0;
          q=new ArrayDeque<>();
          q.addFirst(new Node(0,0));
          for(int i=0;i<K;i++){
              StringTokenizer st = new StringTokenizer(br.readLine());
              int x = Integer.parseInt(st.nextToken());
              int y = Integer.parseInt(st.nextToken());
              board[x-1][y-1]=1;
          }
  
          L = Integer.parseInt(br.readLine());
          char[]turn=new char[10000];
          Arrays.fill(turn,'N');
  
          for(int i=0;i<L;i++){
              StringTokenizer st = new StringTokenizer(br.readLine());
              int X = Integer.parseInt(st.nextToken());
              char C = st.nextToken().charAt(0);
              turn[X]=C;
          }
  
          while(flag){
              move();
              if(turn[index]=='D') pos++;
              else if(turn[index]=='L') pos--;
              if(pos==-1) pos=3;
              else if(pos==4) pos=0;
              index++;
          }
          System.out.println(index-1);
      }static void move(){
          Node head=q.peekLast();
          Node tail=q.peekFirst();
  
          if(flag){
              int nowX=head.x+dx[pos];
              int nowY=head.y+dy[pos];
              if(check(nowX,nowY)){
                  if(board[nowX][nowY]==1){
                      board[nowX][nowY]=2;
                      q.addLast(new Node(nowX,nowY));
                  }else{
                      board[tail.x][tail.y]=0;
                      q.poll();
                      board[nowX][nowY]=2;
                      q.addLast(new Node(nowX,nowY));
                  }
              }
          }
      }static boolean check(int x, int y){
          if(x<0||y<0||x>=N||y>=N|| board[x][y]==2) {
              flag=false;
              return false;
          }
          else return true;
      }static void print(){
          for(int i=0;i<N;i++){
              for(int j=0;j<N;j++){
                  System.out.print(board[i][j]+" ");
              }
              System.out.println();
          }
      }
  }

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