Java program for spiral matrix

Outer spiral matrix– arrows are from boundary to core element. Inner Spiral matrix– Arrows are from core elements to boundary elements.

import java.util.*;     //for importing scanner class

class spiral

{

public static void main(String args[])

{

Scanner obj=new Scanner(System.in);   //can also be done by BufferReader. But then use: import.java.io.*;

System.out.print("\nEnter the size of matrix (nxn):");

int n=obj.nextInt();

int a[][]=new int[n][n];

System.out.println("Your matrix is of order "+n+"x"+n+"\n");

int d,c,i,j,l,t,m,k;

d=n-1;

c=n*n+1;     // if its 3x3 matrix then 1-9 elements are filled. So c=10. afterwards --c making 9,8,.....1

for(i=0;i<=(n+1)/2;i++)

{

for(j=i;j<=d;j++)   //first from west to east

a[i][j]=--c;

for(l=i+1;l<=d;l++)   //    north to south

a[l][d]=--c;

 

for(k=d-1;k>=i;k--)      //east to west

a[d][k]=--c;

 

for(m=d-1;m>i;m--)   //south to north

a[m][i]=--c;

 

d--;               // reducing the size of spiral

}

 

for(i=0;i<n;i++)

{

for(j=0;j<n;j++)

System.out.print(a[i][j]+"\t");

System.out.println();

}

}

}