********Судоку******** http://acmp.ru/index.asp?main=task&id_task=88

sudoku.java

import java.io.*;
import java.math.BigInteger;
import java.util.*;

public class Main{ 
    
  public static void main(String[] argv) throws IOException,Exception{
    new Main().run();
  }
 
  public static StreamTokenizer sc ; 
  public static int nextInt() throws Exception{ 
    sc.nextToken(); 
    return (int)sc.nval; 
  } 

  public void run() throws IOException,Exception{
    sc = new StreamTokenizer(new BufferedReader(new FileReader("input.txt")));   
    int n = nextInt();
    int n2 = (int)Math.pow(n,2);
    Boolean[] rows_fill =  new Boolean[n2];
    Boolean[][] column_fill =  new Boolean[n2][n2];
    for (int i = 0; i < column_fill.length; i++) {
        Arrays.fill(column_fill[i], false);
    }
    int[][] temp = new int[n][n2];
    
    for (int i = 0; i < n; i++) {
        Arrays.fill(rows_fill, false);
         
        for (int j = 0; j < n; j++) {
            for (int k = 0; k < n2; k++) {
                temp[j][k] = nextInt();
                if (temp[j][k] > n2 || temp[j][k] < 1) {
                    print_answer(false);
                }
                rows_fill[temp[j][k]-1] = true;
                column_fill[temp[j][k]-1][k] = true;
            }
            answer_exit(rows_fill);
        }
        Arrays.fill(rows_fill, false);
        
        for (int j = 0; j < n2; j+=n) {
            for (int k = 0; k < n; k++) {
                for (int l = j; l < n; l++) {
                    if (temp[k][l] == 0) {
                        continue;
                    }
                    rows_fill[temp[k][l]-1] = true;
                }
            }
            answer_exit(rows_fill);
        }
      
    }
    for (int i = 0; i < column_fill.length; i++) {
        answer_exit(column_fill[i]);
    }
    print_answer(true);
  }
  
  public static void answer_exit(Boolean[] fillen) throws FileNotFoundException {
    if (Arrays.asList(fillen).contains(false)) {
        print_answer(false);
    }
  } 
  public static void print_answer(Boolean answer) throws FileNotFoundException {
        PrintWriter pw = new PrintWriter(new File("output.txt"));
        String result = answer ? "Correct" : "Incorrect";
        pw.write(result);
        pw.close();
        System.exit(0);
  }
}