This is my program to print natural numbers from 1 to N^2 in a clockwise spiral. I’m getting the following error
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index -2147483648
out of bounds for length 3
at Spiral.main(Spiral.java:13)
This is my program
class Spiral{
public static void main(String[] args) {
System.out.println("Enter value of N");
Scanner sc=new Scanner(System.in);
int N=sc.nextInt();
int arr[][]=new int[N][N];
int r1=0, c1=0, r2=N-1, c2=N-1, flag=1; int i=0,j=0;
while(flag<=N*N)
{ for(j=c1;j<=c2;j++)
arr[r1][j]=flag++;
for( i=r1+1;i<=r2;i++)
arr[i][c2]=flag++; //this is the line of error
for(j=c2-1;j>=c1;j--)
arr[r2][j]=flag++;
for(i=r2-1; i>r1+1;i--)
arr[i][c1]=flag++;
r1++; r2--; c1++; c2--;
}
System.out.println("The Circular Matrix is:");
for( i=0;i<N;i++)
{
for( j=0;j<N;j++)
{
System.out.print(arr[i][j]+ "\t");
}
System.out.println();
}
}
}
The code works fine for N=2 but starts giving this error for N=3,4 etc. If N=3, the greatest value of arr[i][c2] will be arr[2][2] which falls in the range of a 3x3 matrix. Could someone explain why I’m getting this error then?
Increment/decrement r1
, c2
, r2
, and c1
appropriately after their corresponding for loops rather than at the end of the while loop:
import java.util.Scanner;
class Spiral {
public static void main(String[] args) {
System.out.println("Enter value of N");
Scanner sc = new Scanner(System.in);
int N = sc.nextInt();
int[][] arr = new int[N][N];
int r1 = 0, c1 = 0, r2 = N - 1, c2 = N - 1, flag = 1;
int i = 0, j = 0;
while (flag <= N * N) {
for (j = c1; j <= c2; j++)
arr[r1][j] = flag++;
r1++;
for (i = r1; i <= r2; i++)
arr[i][c2] = flag++;
c2--;
for (j = c2; j >= c1; j--)
arr[r2][j] = flag++;
r2--;
for (i = r2; i >= r1; i--)
arr[i][c1] = flag++;
c1++;
}
System.out.println("The Circular Matrix is:");
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
System.out.print(arr[i][j] + "\t");
}
System.out.println();
}
}
}
Example Usage 1:
Enter value of N
4
The Circular Matrix is:
1 2 3 4
12 13 14 5
11 16 15 6
10 9 8 7
Example Usage 2:
Enter value of N
7
The Circular Matrix is:
1 2 3 4 5 6 7
24 25 26 27 28 29 8
23 40 41 42 43 30 9
22 39 48 49 44 31 10
21 38 47 46 45 32 11
20 37 36 35 34 33 12
19 18 17 16 15 14 13