InputChecker of problemE in WUPC2nd.

InputCheckerE.java

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.InputStreamReader;

public class InputCheckerE {
  public static void main(String[] args) throws Exception {
    String[] substasks = new String[]{"nonloop", "loop"};
    for (String substask : substasks) {
      File inputDir = new File("/path/to/the/input/data/" + substask);
      for (File file : inputDir.listFiles()) {
        BufferedReader reader = new BufferedReader(new FileReader(file));      
        if (!check(reader, "loop".equals(substask) ? 1 : 0)) {
          System.err.println("err:" + file.getName());
        } else {
          System.err.println("ok");  
        }
        reader.close();
      }
    }
  }

  private static boolean check(BufferedReader reader, int allowedLoop) {
    try {
      String[] line = reader.readLine().split(" ");
      if (line.length != 3) {
        return false;
      }
      int N = Integer.valueOf(line[0]);
      int M = Integer.valueOf(line[1]);
      int K = Integer.valueOf(line[2]);
      if (1 <= N && N <= 100) {
      } else {
        System.err.println("invalid N");
        return false;
      }
      
      if (0 <= M && M <= N) {
      } else {
        System.err.println("invalid M");
        return false;
      }
      
      if (1 <= K && K <= N) {
      } else {
        System.err.println("invalid K");
        return false;
      }
      
      boolean[][] graph = new boolean[N+1][N+1];
      int[] degs = new int[N+1];
      for (int i = 0 ; i < M ; i++) {
        String[] road = reader.readLine().split(" ");
        if (road.length != 3) {
          return false;
        }
        int f = Integer.valueOf(road[0]);
        int t = Integer.valueOf(road[1]);
        int c = Integer.valueOf(road[2]);
        if (1 <= f && f <= N) {
        } else {
          System.err.println("invalid f");
          return false;
        }
        if (1 <= t && t <= N) {
        } else {
          System.err.println("invalid t");
          return false;
        }
        if (1 <= c && c <= 1000000) {
        } else {
          System.err.println("invalid cost");
          return false;
        }
        if (f == t) {
          System.err.println("self loop");
          return false;
        }
        if (graph[f][t]) {
          System.err.println("double");
          return false;
        }
        graph[f][t] = true;
        graph[t][f] = true;
        degs[f]++;
        degs[t]++;
      }
      
      
      while (true) {
        boolean updated = false;
        for (int i = 1 ; i <= N ; i++) {
          if (degs[i] == 1) {
            updated = true;
            degs[i]--;
            for (int j = 1 ; j <= N ; j++) {
              if (i == j || !graph[i][j]) {
                continue;
              }
              degs[j]--;
            }
          }
        }
        if (!updated) {
          break;
        }
      }
      
      
      if (allowedLoop == 0) {
        for (int i = 1 ; i <= N ; i++) {
          if (degs[i] >= 1) {
            return false;
          }
        }
      } else {
        int gcnt = 0;
        visited = new boolean[N+1];
        for (int i = 1 ; i <= N ; i++) {
          if (degs[i] >= 2) {
            if (degs[i] != 2) {
              System.err.println("invalid degrees:" + degs[i]);
              return false;
            }
            if (!visited[i]) {
              gcnt++;
              dfs(i, N, graph);
            }
          }
        }
        if (gcnt != 1) {
          System.err.println("invalid number of loops:" + gcnt);
          return false;
        }
      }
      return true;
    } catch (Exception e) {
      return false;
    }
  }
  
  static boolean[] visited;
  
  public static void dfs(int i, int N, boolean[][] g) {
    if (visited[i]) {
      return;
    }
    visited[i] = true;
    for (int j = 1 ; j <= N ; j++) {
      if (g[i][j]) {
        dfs(j, N, g);
      }
    }
  }
}