Spiral Matrix
Write a program
which takes N as input, where N is the order of an square matrix.
Generate the spiral matrix of order N.
INPUT:
N = 1
OUTPUT:
1
INPUT:
N=2
OUTPUT
1 2
4 3
INPUT:
N=3
OUTPUT
1 2
3
8 9
4
7 6
5
INPUT:
N=4
OUTPUT
1 2
3 4
12 13
14 5
11 16
15 6
10 9
8 7
INPUT:
N=7
OUTPUT
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
Logic: Go through the code!!!!!! All the best!
JAVA CODE
import java.util.*;
public class ISC1998Spiral {
public static void main(String[] args) {
int N, val = 0, row, col, ri, ci;
int i, j;
int[][] matrix;
Scanner in = new Scanner(System.in);
System.out.println("Enter the order of the matrix:");
N = in.nextInt();
matrix = new int[N + 1][N + 1];
for (i = 1; i <= N; i++) {
for (j = 1; j <= N; j++) {
matrix[i][j] = 1;
}
}
row = col = 1;
ri = (N - (N - 2));
ci = (N - (N - 1));
SpiralGeneration sp = new SpiralGeneration();
System.out.println("OUTPUT:");
sp.spiral(matrix, N, row, col, val, ri, ci);
for (i = 1; i <= N; i++) {
for (j = 1; j <= N; j++) {
String s = String.valueOf(matrix[i][j]);
while (s.length() < 4) {
s += " ";
}
System.out.print(s);
}
System.out.println();
}
}
}
class SpiralGeneration {
public void spiral(int[][] matrix, int N, int row, int col, int val, int ri, int ci) {
int a, b, tmp, i, j, l = 0;
a = row;
b = col;
tmp = val + 1;
if (N == 1 || N == 2) // stopping condition
{
if (N == 1) {
matrix[row][col] = tmp;
} else {
matrix[row][col] = tmp;
matrix[row][col + 1] = tmp + 1;
matrix[row + 1][col + 1] = tmp + 2;
matrix[row + 1][col] = tmp + 3;
}
} else {
for (b = 1; b <= N; b++) {
matrix[row][b - 1 + col] = tmp++;
if (row != b - 1 + col)
matrix[b - 1 + col][row] = (4 * N - 2) - (matrix[row][b - 1 + col] - val) + val;
}
b--;
for (a = 1; a <= N - 1; a++) {
matrix[a + row][b - 1 + col] = tmp++;
if (a + row != b - 1 + col)
matrix[b - 1 + col][a + row] = (4 * N - 2) - (matrix[a + row][b - 1 + col] - val) + val;
}
val = matrix[ri][ci];
spiral(matrix, N - 2, ++row, ++col, val, ++ri, ++ci);
}
}
}
#include<stdio.h>
#include<malloc.h>
void spiral(int **matrix,int N, int row, int col, int val,int ri,int ci);
int main() {
int N,val=0,row,col,ri,ci;
int i,j;
int **matrix;
printf("\n Enter the order of the matrix:");
scanf("%d",&N);
matrix=(int **)malloc((N+1)*sizeof(int*));
for(i=0;i<=N;i++)
matrix[i]=(int *)malloc((N+1)*sizeof(double));
for(i=1;i<=N;i++) {
for(j=1;j<=N;j++) {
matrix[i][j]=1;
}
}
row=col=1;
ri = (N-(N-2));
ci = (N-(N-1));
spiral(matrix,N,row,col,val,ri,ci);
printf("\n");
for(i=1;i<=N;i++) {
for(j=1;j<=N;j++) {
if ( i== 1)
printf("%d ",matrix[i][j]);
else
printf("%d ",matrix[i][j]);
}
printf("\n");
}
return 0;
}
void spiral(int **matrix,int N,int row,int col,int val,int ri,int ci) {
int a,b,tmp,i,j,l=0;
a = row;
b = col;
tmp = val +1;
if (N== 1 || N==2 ) // stopping condition
{
if ( N == 1) {
matrix[row][col] = tmp;
}
else {
matrix[row][col] = tmp;
matrix[row][col+1] = tmp+1;
matrix[row+1][col+1] = tmp+2;
matrix[row+1][col] = tmp+3;
}
}
else {
for( b = 1 ; b <= N ; b++) {
matrix[row][b-1+col] = tmp++;
if( row!=b-1+col )
matrix[b-1+col][row] = (4*N-2)-(matrix[row][b-1+col]-val) + val ;
}
b--;
for( a = 1 ; a <= N-1; a++) {
matrix[a+row][b-1+col] = tmp++;
if( a+row!=b-1+col)
matrix[b-1+col][a+row] = (4*N-2)-(matrix[a+row][b-1+col]-val) +val;
}
val = matrix[ri][ci];
spiral(matrix,N-2,++row,++col,val,++ri,++ci);
}
}
Python Code
Passing List to function, recursion in python
def SpiralMatrix():
N = int(input("Enter the order of the Magic Square (odd):"))
matrix=[[ 0 for row in range(N+2)]for col in range(N+2)]
for i in range (N+2):
for j in range (N+2):
matrix[i][j]=1
row=col=1
val = 0
ri = (N-(N-2))
ci = (N-(N-1))
def spiral(matrix,N,row,col,val,ri,ci):
a = row
b = col
tmp = val +1
#print a,b,tmp
if N== 1 or N==2:
if N == 1:
matrix[row][col] = tmp;
else:
matrix[row][col] = tmp
matrix[row][col+1] = tmp+1
matrix[row+1][col+1] = tmp+2
matrix[row+1][col] = tmp+3
else:
for b in range(N):
b = b+1
matrix[row][b-1+col] = tmp
tmp = tmp+1
if row != b-1+col:
matrix[b-1+col][row] = (4*N-2)-(matrix[row][b-1+col]-val) + val
for a in range(N-1):
a = a+1
matrix[a+row][b-1+col] = tmp
tmp = tmp+1
if a+row != b-1+col:
matrix[b-1+col][a+row] = (4*N-2)-(matrix[a+row][b-1+col]-val) +val
val = matrix[ri][ci]
row = row+1
col = col+1
ri = ri+1
ci = ci+1
spiral(matrix,N-2,row,col,val,ri,ci)
spiral(matrix,N,row,col,val,ri,ci)
print ("OUTPUT~~ SPIRAL MATRIX:")
for i in range (N):
for j in range (N):
print (matrix[i+1][j+1],end =' ')
print()
SpiralMatrix()
