Magic Square in Java: Why always prints: Magic Squares cannot be created?

Question

In the code below i try to read a file with the size of a 2d array and the numbers for each cell. Then the program must find a number that can be added in the cell with a zero value in magic array. All this in order to create magic squares based on the initialized magic array with the elements of the external file. The problem is that i always get the message "magic squares cannot be created" even when the if statement in next_successor method get true from all the arguments? where is the problem? i got really stuck any help will be appreciated!

so i think the main problem is with the methods:

next_successor
check_row
check_column
check_diagonals

The rules that i have to follow in order to create the methods are: In order for current_number to be inserted into magic[row,column], the following checks (by check_row(), check_column() and check_diagonals()) should be made:

For each of the row, column, and possibly main diagonals (in the case of row=column or row=N-column-1) to which position magic[row,column] belongs, and for each current_number that does not has yet been inserted into the magic square (according to the value used[current_number-1]), we perform the following checks to decide whether current_number can be inserted into magic[row,column]:
Suppose (in the row or column or main diagonal where the position magic[row,column]) is located after the number current_number is placed in the position magic[row,column], m positions have been filled, so there are N-m empty positions left to be filled.
Let 𝑠 be the sum of the numbers already in the row or column or main diagonal (including current_number).
Let 𝑎 be the sum of the 𝑁−𝑚 smallest numbers (from 1 to N*N) not yet entered into the magic square (according to the table used) and 𝑏 the sum of the 𝑁−𝑚 largest numbers not yet entered (similarly) . If 𝑚=𝑁 then 𝑎=𝑏=0.
Let 𝐶 be the magic constant. If 𝑠+𝑎>𝐶 or 𝑠+𝑏<𝐶, for some row or column or main diagonal to which magic[row, column] belongs, then current_number cannot be inserted into position magic[row,column ], i.e. the respective check_row(), check_column() and check_diagonals() will return false, otherwise they will all return true.

the txt external file has the following elements:

6
0 0 13 0 20 0
0 15 0 0 0 12
8 0 2 0 31 0
0 14 0 7 0 1
28 0 0 0 0 0
0 0 6 0 0 21

import java.io.*;
import java.util.*;


public class MainSolver{
    static ArrayList stuckAL;
    static Stack stuckST;
    static LinkedList stuckLL;
    static int datastructure; 
    static int N = 0;
    static int[][] input;
    
    public static void main() throws IOException {
        //THE PROGRAM READS THE EXTERNAL FILE
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the file name: ");
        String fileName = sc.next();
        System.out.println("Enter data structure to use: (arraylist, stack, queue, linkedlist): ");
        System.out.println("1: arraylist");
        System.out.println("2: stack");
        System.out.println("3: queue");
        System.out.println("4: linkedlist");
        datastructure = sc.nextInt();
        
        File file = new File(fileName);
        Scanner fileScanner = new Scanner(file);
        
        N = fileScanner.nextInt();
        input = new int[N][N];

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                input[i][j] = fileScanner.nextInt();
            }
        }
        
        MagicSquare.size = N;
        MagicSquare ms = new MagicSquare();
        
        for(int i=0; i=1 && number<=N*N && row>=0 && row=0 && col C || sum + b < C) {
            System.out.println("row gives false!");
            return false;
        }
        System.out.println("row gives true!");
        return true;
    }
    //METHOD THAT: returns true if current_number is consistent with the column numbers of magic[row,column], otherwise returns false.
    public boolean check_column(){
        int sum = current_number;
        int m = numbers;
        int emptyPositions = N - m;
        int a = getSumOfSmallestElementsNotUsed();
        int b = getSumOfLargestElementsNotUsed();
        System.out.println("current number being tested in column: "+current_number);
        for (int i = 0; i < N; i++) {
            if (magic[i][column] != 0) {
                sum += magic[i][column];
            }
        }
        System.out.println("sum of numbers in column: "+sum);
        if (sum + a > C || sum + b < C) {
            System.out.println("column gives false!");
            return false;
        }
        System.out.println("column gives true!");
        return true;
    }
    //METHOD THAT: which will return true if current_number is consistent with the numbers of each of the two main diagonals of the magic square, provided that magic[row,column] belongs to one or the other or both of the main diagonals of the magic square respectively, otherwise it will return false.
    public boolean check_diagonals(){
        int sum = current_number;
        int m = numbers;
        int emptyPositions = N - m;
        int a = getSumOfSmallestElementsNotUsed();
        int b = getSumOfLargestElementsNotUsed();
        System.out.println("current number being tested in diagonals: "+current_number);
        if (row == column) { //main diagonal
            for (int i = 0; i < N; i++) {
                if (magic[i][i] != 0) {
                    sum += magic[i][i];
                }
            }
        } else if (row == N-column-1) { //other diagonal
            for (int i = 0; i < N; i++) {
                if (magic[i][N-i-1] != 0) {
                    sum += magic[i][N-i-1];
                }
            }
        }
        System.out.println("sum of numbers in diagonal: "+sum);
        if (sum + a > C || sum + b < C) {
            System.out.println("diagonals gives false!");
            return false;
        }
        System.out.println("diagonals gives true!");
        return true;
    }
    //METHOD THAT: calculate the sum of the 2 first empty elements of used array and therefore the smallest
    public int getSumOfSmallestElementsNotUsed(){
        int sum = 0;
        int count = 0;
        for (int i = 0; i < used.length; i++) {
            if (!used[i]) {
                sum += (i + 1);
                count++;
            }
            if (count == 2) {
                break;
            }
        }
        System.out.println("sum of 2 smallest elements: "+sum);
        return sum;
        
    }
    //METHOD THAT: calculate the sum of the 2 last empty elements of used array and therefore the largest
    public int getSumOfLargestElementsNotUsed(){
        int sum = 0;
        int count = 0;
        for (int i = used.length - 1; i >= 0; i--) {
            if (!used[i]) {
                sum += (i + 1);
                count++;
            }
            if (count == 2) {
                break;
            }
        }
        System.out.println("sum of 2 largest elements: "+sum);
        return sum;
    }

    
    public boolean isComplete() {
        return numbers == N*N;
    }

    public void display(int array[][]) {
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                System.out.print(array[i][j] + " ");
            }
            System.out.println();
        }
        System.out.println();
    }
    
    public void check_used(){
        int i,j;
        int k=0;

        for(i=0; i

Magic Square in Java: Why always prints: Magic Squares cannot be created?

Answers (1)

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