Magic Square

Magic Squares.An nXn matrix is filled with the numbers 1,2,3,.....n2 is a magic square if the sum of elements in each row,in each column and in two diagonals is the same value.For example ..

Wrie a program that reads in n2 numbers from the keyboard and tests whether they form a magic square when put in array form.You need to test the following three features:

• Did the user enter n2 numbers for some n ?
• Does each of the numbers occur exactly once in the user input?
• Does the numbers when put in an array form a magic square?

SOLUTION: 

 
//Importing Scanner calss for reading numbers
import java.util.Scanner;

public class MagicSquare{
 
 public static void main(String args[]){
  //Creating Scanner class object
  Scanner input = new Scanner(System.in);
  //Temporary array for storing numbers.
  int temp[] = new int[525];
  //Some temp variables
  int i=0;
  int j=0;
  
  //Reading numbers for magic square.
  do{
   System.out.println("Please enter the number (Enter -1 to stop reading)");
   i=input.nextInt();
   temp[j]=i;
   j++;
  }while(i!=-1);
  j--;
  
  //Checking wether entered number are n^2 or not.
  int n=(int)Math.sqrt(j);
  if(Math.sqrt(j)!=n){
   System.out.println("Insufficient numbers.");
   return;
  }
  
  //Performing further operations
  System.out.println("User enters n^2 numbers.");
  //Creating magic square like a matrix
  int k=0;
  int mat[][]=new int[n][n];
  for( i = 0; i < n; i++ ) {
   for( j = 0; j < n; j++ ) {
    mat[i][j]=temp[k];
    k++;
   }
  }
  
  //Printing the matrix on screen
  for( i = 0; i < n; i++ ) {
   for( j= 0; j < n; j++)
    System.out.print(mat[i][j]+" ");
   System.out.println();
  }
  
  //Checking for duplicate numbers
  int check=0;
  boolean flag=false;
  test: for( i = 0; i < n; i++ ) {
   for( j= 0; j < n; j++) {
    check=mat[i][j];
    for( k = 0; k < n; k++ ) {
     for(int l = 0; l < n; l++ ) {
      if(check==mat[k][l] && (i!=k || j!=l)) {
       flag=true;
       break test;
      }
     }
    }
   } 
  }
  if(flag==true)
   System.out.println("Magic square has duplicate numbers.");
  else
   System.out.println("Magic square does not has duplicate numbers.");
  
  //Checking for magic square.
  magicSquare(mat,n);
 }
 
 //Method for checking magic square.
 static void magicSquare(int arr[][],int num){
  //some variables
  int sumRow[]=new int[num];
  int sumCol[]=new int[num];
  int sumDig[]=new int[2];
  boolean flag=false;
  
  //Adding rows and columns
  for ( int i = 0; i < num; i++ ) { 
   for( int j = 0; j < num; j++ ) {
    sumRow[i]=sumRow[i]+arr[i][j];
    sumCol[i]=sumCol[i]+arr[i][j];
   }
  }
  
  //Adding diagonals
  for( int i = 0; i < num; i++ ) {
   sumDig[0]=sumDig[0]+arr[i][i];
   sumDig[1]=sumDig[1]+arr[i][num-i-1];
  }
  
  //Checking for duplicate entries.
  int sum=sumDig[0];
  for( int i = 0; i < num; i++) {
   if((sum==sumRow[i] && sum ==sumCol[i])&&(sum==sumDig[1])) {
    flag=true;
   }
   else{
    flag= false;
   }
  }
  
  //Printing output
  if(flag)
   System.out.println("Magic square !!");
  else
   System.out.println(" It's not a magic square!!");
 }
}