提交UVA-1665代码至在线判题系统遇Runtime Error求排查

我的代码在本地用样例测试正常，但提交到在线判题系统时出现Runtime Error。已经将类名改为public class Main，但问题依旧。以下是我的代码：

import java.io.BufferedReader;
import java.io.InputStreamReader;

class problemb {
  static int dx[] = {-1, 0, 1, 0};
  static int dy[] = {0, 1, 0, -1};

  static int[][] map;
  static boolean[][] visited;

  static int n, m;
  static int t;
  static int[] years;

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int z = Integer.parseInt(br.readLine());

    for (int i = 0; i < z; i++) {
      String[] nm = br.readLine().split(" ");
      n = Integer.parseInt(nm[0]);
      m = Integer.parseInt(nm[1]);

      map = new int[n][m];
      visited = new boolean[n][m];

      for (int j = 0; j < n; j++) {
        String[] row = br.readLine().split(" ");
        for (int k = 0; k < m; k++) {
          map[j][k] = Integer.parseInt(row[k]);
        }
      }

      t = Integer.parseInt(br.readLine());
      years = new int[t];

      String[] tValues = br.readLine().split(" ");
      for (int j = 0; j < t; j++) {
        years[j] = Integer.parseInt(tValues[j]);
      }
      br.close();
      
      int[] results = new int[t];
      
      for (int j = 0; j < t; j++) {
        int year = years[j];
        int areas = 0;
      
        // Reset the visited array for the current year
        visited = new boolean[n][m];
      
        for (int y = 0; y < n; y++) {
          for (int x = 0; x < m; x++) {
            if (!visited[y][x] && map[y][x] > year) {
              areas++;
              bfs(y, x, year);
            }
          }
        }
      
        results[j] = areas;
      }
      
      for (int j = 0; j < results.length; j++) {
        System.out.print(results[j]);
        if (j < results.length - 1) {
          System.out.print(" ");
        }
      }
      System.out.println();
    }
  }
  static void bfs(int y, int x, int year) {
    int[][] queue = new int[n * m][2];
    int head = 0, tail = 0;
    queue[tail][0] = y;
    queue[tail][1] = x;
    tail++;
    visited[y][x] = true;
  
    while (head < tail) {
      int yy = queue[head][0];
      int xx = queue[head][1];
      head++;
  
      for (int i = 0; i < 4; i++) {
        int ny = yy + dy[i];
        int nx = xx + dx[i];
  
        if (ny < 0 || ny >= n || nx < 0 || nx >= m || visited[ny][nx] || map[ny][nx] <= year) {
          continue;
        }
  
        visited[ny][nx] = true;
        queue[tail][0] = ny;
        queue[tail][1] = nx;
        tail++;
      }
    }
  }
}

问题根源 #

1. 提前关闭输入流：在第一个测试用例处理完后就执行br.close()，如果测试用例组数z>1，后续读取输入时会触发IO异常，直接导致Runtime Error。
2. 输入读取不健壮：
   • 使用split(" ")分割输入时，若遇到连续空格或首尾空格，会生成空字符串，调用Integer.parseInt时抛出异常。
   • 假设年份输入都在同一行，但实际判题系统的输入可能将年份拆分为多行，导致读取不完整。

修正后的代码 #

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
    static int dx[] = {-1, 0, 1, 0};
    static int dy[] = {0, 1, 0, -1};

    static int[][] map;
    static boolean[][] visited;

    static int n, m;
    static int t;
    static int[] years;

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int z = Integer.parseInt(br.readLine().trim());

        for (int i = 0; i < z; i++) {
            // 读取n和m，跳过空行
            String nmLine;
            do {
                nmLine = br.readLine().trim();
            } while (nmLine.isEmpty());
            String[] nm = nmLine.split("\\s+");
            n = Integer.parseInt(nm[0]);
            m = Integer.parseInt(nm[1]);

            map = new int[n][m];
            visited = new boolean[n][m];

            for (int j = 0; j < n; j++) {
                String rowLine;
                do {
                    rowLine = br.readLine().trim();
                } while (rowLine.isEmpty());
                String[] row = rowLine.split("\\s+");
                for (int k = 0; k < m; k++) {
                    map[j][k] = Integer.parseInt(row[k]);
                }
            }

            // 读取t，跳过空行
            String tLine;
            do {
                tLine = br.readLine().trim();
            } while (tLine.isEmpty());
            t = Integer.parseInt(tLine);
            years = new int[t];

            // 读取年份，支持跨多行输入
            int count = 0;
            while (count < t) {
                String yearLine = br.readLine().trim();
                if (yearLine.isEmpty()) continue;
                String[] tValues = yearLine.split("\\s+");
                for (String val : tValues) {
                    if (count >= t) break;
                    years[count++] = Integer.parseInt(val);
                }
            }
            
            int[] results = new int[t];
            
            for (int j = 0; j < t; j++) {
                int year = years[j];
                int areas = 0;
            
                visited = new boolean[n][m];
            
                for (int y = 0; y < n; y++) {
                    for (int x = 0; x < m; x++) {
                        if (!visited[y][x] && map[y][x] > year) {
                            areas++;
                            bfs(y, x, year);
                        }
                    }
                }
            
                results[j] = areas;
            }
            
            for (int j = 0; j < results.length; j++) {
                System.out.print(results[j]);
                if (j < results.length - 1) {
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
        br.close();
    }

    static void bfs(int y, int x, int year) {
        int[][] queue = new int[n * m][2];
        int head = 0, tail = 0;
        queue[tail][0] = y;
        queue[tail][1] = x;
        tail++;
        visited[y][x] = true;
    
        while (head < tail) {
            int yy = queue[head][0];
            int xx = queue[head][1];
            head++;
    
            for (int i = 0; i < 4; i++) {
                int ny = yy + dy[i];
                int nx = xx + dx[i];
    
                if (ny < 0 || ny >= n || nx < 0 || nx >= m || visited[ny][nx] || map[ny][nx] <= year) {
                    continue;
                }
    
                visited[ny][nx] = true;
                queue[tail][0] = ny;
                queue[tail][1] = nx;
                tail++;
            }
        }
    }
}

内容的提问来源于stack exchange，提问作者derki