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2013
11-11

POJ 2632 Crashing Robots [解题报告] Java

Crashing Robots

问题描述 :

In a modernized warehouse, robots are used to fetch the goods. Careful planning is needed to ensure that the robots reach their destinations without crashing into each other. Of course, all warehouses are rectangular, and all robots occupy a circular floor space with a diameter of 1 meter. Assume there are N robots, numbered from 1 through N. You will get to know the position and orientation of each robot, and all the instructions, which are carefully (and mindlessly) followed by the robots. Instructions are processed in the order they come. No two robots move simultaneously; a robot always completes its move before the next one starts moving.

A robot crashes with a wall if it attempts to move outside the area of the warehouse, and two robots crash with each other if they ever try to occupy the same spot.

输入:

The first line of input is K, the number of test cases. Each test case starts with one line consisting of two integers, 1 <= A, B <= 100, giving the size of the warehouse in meters. A is the length in the EW-direction, and B in the NS-direction.

The second line contains two integers, 1 <= N, M <= 100, denoting the numbers of robots and instructions respectively.

Then follow N lines with two integers, 1 <= Xi <= A, 1 <= Yi <= B and one letter (N, S, E or W), giving the starting position and direction of each robot, in order from 1 through N. No two robots start at the same position.



Figure 1: The starting positions of the robots in the sample warehouse


Finally there are M lines, giving the instructions in sequential order.

An instruction has the following format:

< robot #> < action> < repeat>

Where is one of
  • L: turn left 90 degrees,
  • R: turn right 90 degrees, or
  • F: move forward one meter,

and 1 <= < repeat> <= 100 is the number of times the robot should perform this single move.

输出:

Output one line for each test case:
  • Robot i crashes into the wall, if robot i crashes into a wall. (A robot crashes into a wall if Xi = 0, Xi = A + 1, Yi = 0 or Yi = B + 1.)
  • Robot i crashes into robot j, if robots i and j crash, and i is the moving robot.
  • OK, if no crashing occurs.

Only the first crash is to be reported.

样例输入:

4
5 4
2 2
1 1 E
5 4 W
1 F 7
2 F 7
5 4
2 4
1 1 E
5 4 W
1 F 3
2 F 1
1 L 1
1 F 3
5 4
2 2
1 1 E
5 4 W
1 L 96
1 F 2
5 4
2 3
1 1 E
5 4 W
1 F 4
1 L 1
1 F 20

样例输出:

Robot 1 crashes into the wall
Robot 1 crashes into robot 2
OK
Robot 1 crashes into robot 2

解题代码:

import java.util.Scanner;  
    
 enum Direction {  
     N, S, W, E  
 }  
    
 class Robot {  
     int id;  
     int x;  
     int y;  
     Direction direction;  
    
     public Robot(int i, int x, int y, String direction) {  
         this.id = i;  
         this.x = x;  
         this.y = y;  
         if (direction.equalsIgnoreCase("N"))  
             this.direction = Direction.N;  
         else if (direction.equalsIgnoreCase("S"))  
             this.direction = Direction.S;  
         else if (direction.equalsIgnoreCase("W"))  
             this.direction = Direction.W;  
         else if (direction.equalsIgnoreCase("E"))  
             this.direction = Direction.E;  
     }  
    
     public void move(String command) {  
         if (command.equalsIgnoreCase("F")) {  
            switch (this.direction) {  
            case N:  
                 this.y++;  
                 break;  
             case S:  
                 this.y--;  
                 break;  
             case W:  
                 this.x--;  
                 break;  
             case E:  
                 this.x++;  
                 break;  
             }  
         } else {  
             this.rotate(command);  
         }  
     }  
    
     public void rotate(String s) {  
         if (s.equalsIgnoreCase("L")) {  
             switch (this.direction) {  
             case N:  
                 this.direction = Direction.W;  
                 break;  
             case S:  
                 this.direction = Direction.E;  
                 break;  
             case W:  
                 this.direction = Direction.S;  
                 break;  
             case E:  
                 this.direction = Direction.N;  
                 break;  
             }  
         } else {  
             switch (this.direction) {  
             case N:  
                 this.direction = Direction.E;  
                 break;  
             case S:  
                 this.direction = Direction.W;  
                 break;  
             case W:  
                 this.direction = Direction.N;  
                 break;  
             case E:  
                 this.direction = Direction.S;  
                 break;  
             }  
         }  
     }  
 }  
    
public class Main {  
    
     public static String collision(Robot[] robots, Robot r, int x_dim, int y_dim) {  
        int num = robots.length;  
         if (r.x <= 0 || r.x > x_dim || r.y <= 0 || r.y > y_dim) {  
             return "Robot " + r.id + " crashes into the wall";  
         }  
         for (int i = 0; i < num; i++) {  
             if (r.x == robots[i].x && r.y == robots[i].y  
                     && r.id != robots[i].id) {  
                 return "Robot " + r.id + " crashes into " + "robot " 
                         + robots[i].id;  
             }  
         }  
         return "OK";  
     }  
    
     public static void main(String[] args) {  
    
         Scanner in = new Scanner(System.in);  
         int rounds = in.nextInt();  
         for (int i = 0; i < rounds; i++) {  
             int x_dimension = in.nextInt();  
             int y_dimension = in.nextInt();  
             int num_robots = in.nextInt();  
             String response = "OK", temp;  
             Robot robots[] = new Robot[num_robots];  
             int num_ins = in.nextInt();  
             for (int j = 1; j < num_robots + 1; j++) {  
                 robots[j - 1] = new Robot(j, in.nextInt(), in.nextInt(), in  
                         .next());  
             }  
             for (int k = 0; k < num_ins; k++) {  
                 int r_id = in.nextInt();  
                 String command = in.next();  
                 int num_iteration = in.nextInt();  
                 Robot robot = robots[r_id - 1];  
                 for (int m = 0; m < num_iteration; m++) {  
                     robot.move(command);  
                     temp = collision(robots, robot, x_dimension, y_dimension);  
                     if (response.startsWith("O") && !temp.startsWith("O"))  
                         response = temp;  
                 }  
             }  
             System.out.println(response);  
         }  
     }  
    
 }