Print a given matrix in spiral form

Given a 2D array, print it in spiral form. See the following examples.

Examples:

Input:
        1    2   3   4
        5    6   7   8
        9   10  11  12
        13  14  15  16
Output: 
1 2 3 4 8 12 16 15 14 13 9 5 6 7 11 10 


Input:
        1   2   3   4  5   6
        7   8   9  10  11  12
        13  14  15 16  17  18
Output: 
1 2 3 4 5 6 12 18 17 16 15 14 13 7 8 9 10 11

spiral-matrix

Solution:

C/C++

/* This code is adopted from the solution given  
   @ http://effprog.blogspot.com/2011/01/spiral-printing-of-two-dimensional.html */
  
#include <stdio.h> 
#define R 3 
#define C 6 
  
void spiralPrint(int m, int n, int a[R][C]) 
{ 
    int i, k = 0, l = 0; 
  
    /*  k - starting row index 
        m - ending row index 
        l - starting column index 
        n - ending column index 
        i - iterator 
    */
  
    while (k < m && l < n) 
    { 
        /* Print the first row from the remaining rows */
        for (i = l; i < n; ++i) 
        { 
            printf("%d ", a[k][i]); 
        } 
        k++; 
  
        /* Print the last column from the remaining columns */
        for (i = k; i < m; ++i) 
        { 
            printf("%d ", a[i][n-1]); 
        } 
        n--; 
  
        /* Print the last row from the remaining rows */
        if ( k < m) 
        { 
            for (i = n-1; i >= l; --i) 
            { 
                printf("%d ", a[m-1][i]); 
            } 
            m--; 
        } 
  
        /* Print the first column from the remaining columns */
        if (l < n) 
        { 
            for (i = m-1; i >= k; --i) 
            { 
                printf("%d ", a[i][l]); 
            } 
            l++;     
        }         
    } 
} 
  
/* Driver program to test above functions */
int main() 
{ 
    int a[R][C] = { {1,  2,  3,  4,  5,  6}, 
        {7,  8,  9,  10, 11, 12}, 
        {13, 14, 15, 16, 17, 18} 
    }; 
  
    spiralPrint(R, C, a); 
    return 0; 
} 

/div>

Java

// Java program to print a given matrix in spiral form 
import java.io.*; 
  
class GFG  
{ 
    // Function print matrix in spiral form 
    static void spiralPrint(int m, int n, int a[][]) 
    { 
        int i, k = 0, l = 0; 
        /*  k - starting row index 
        m - ending row index 
        l - starting column index 
        n - ending column index 
        i - iterator 
        */
           
        while (k < m && l < n) 
        { 
            // Print the first row from the remaining rows 
            for (i = l; i < n; ++i) 
            { 
                System.out.print(a[k][i]+" "); 
            } 
            k++; 
   
            // Print the last column from the remaining columns  
            for (i = k; i < m; ++i) 
            { 
                System.out.print(a[i][n-1]+" "); 
            } 
            n--; 
   
            // Print the last row from the remaining rows */ 
            if ( k < m) 
            { 
                for (i = n-1; i >= l; --i) 
                { 
                    System.out.print(a[m-1][i]+" "); 
                } 
                m--; 
            } 
   
            // Print the first column from the remaining columns */ 
            if (l < n) 
            { 
                for (i = m-1; i >= k; --i) 
                { 
                    System.out.print(a[i][l]+" "); 
                } 
                l++;     
            }         
        } 
    } 
      
    // driver program 
    public static void main (String[] args)  
    { 
        int R = 3; 
        int C = 6; 
        int a[][] = { {1,  2,  3,  4,  5,  6}, 
                      {7,  8,  9,  10, 11, 12}, 
                      {13, 14, 15, 16, 17, 18} 
                    }; 
        spiralPrint(R,C,a); 
    } 
} 
  
// Contributed by Pramod Kumar 

Python3

# Python3 program to print  
# given matrix in spiral form 
def spiralPrint(m, n, a) : 
    k = 0; l = 0
  
    ''' k - starting row index 
        m - ending row index 
        l - starting column index 
        n - ending column index 
        i - iterator '''
      
  
    while (k < m and l < n) : 
          
        # Print the first row from 
        # the remaining rows  
        for i in range(l, n) : 
            print(a[k][i], end = " ") 
              
        k += 1
  
        # Print the last column from 
        # the remaining columns  
        for i in range(k, m) : 
            print(a[i][n - 1], end = " ") 
              
        n -= 1
  
        # Print the last row from 
        # the remaining rows  
        if ( k < m) : 
              
            for i in range(n - 1, (l - 1), -1) : 
                print(a[m - 1][i], end = " ") 
              
            m -= 1
          
        # Print the first column from 
        # the remaining columns  
        if (l < n) : 
            for i in range(m - 1, k - 1, -1) : 
                print(a[i][l], end = " ") 
              
            l += 1
  
# Driver Code 
a = [ [1, 2, 3, 4, 5, 6], 
      [7, 8, 9, 10, 11, 12], 
      [13, 14, 15, 16, 17, 18] ] 
        
R = 3; C = 6
spiralPrint(R, C, a) 
  
# This code is contributed by Nikita Tiwari. 

C#

// C# program to print a given 
// matrix in spiral form 
using System; 
  
class GFG 
{ 
    // Function print matrix in spiral form 
    static void spiralPrint(int m, int n, int [,]a) 
    { 
        int i, k = 0, l = 0; 
        /* k - starting row index 
        m - ending row index 
        l - starting column index 
        n - ending column index 
        i - iterator 
        */
          
        while (k < m && l < n) 
        { 
            // Print the first row from the remaining rows 
            for (i = l; i < n; ++i) 
            { 
                Console.Write(a[k, i] +" "); 
            } 
            k++; 
  
            // Print the last column from the remaining columns  
            for (i = k; i < m; ++i) 
            { 
                Console.Write(a[i,n - 1]+" "); 
            } 
            n--; 
  
            // Print the last row from the remaining rows */ 
            if ( k < m) 
            { 
                for (i = n-1; i >= l; --i) 
                { 
                    Console.Write(a[m - 1, i]+" "); 
                } 
                m--; 
            } 
  
            // Print the first column from the remaining columns */ 
            if (l < n) 
            { 
                for (i = m-1; i >= k; --i) 
                { 
                    Console.Write(a[i, l] + " "); 
                } 
                l++;  
            }      
        } 
    } 
      
    // Driver program 
    public static void Main ()  
    { 
        int R = 3; 
        int C = 6; 
        int [,]a = { {1, 2, 3, 4, 5, 6}, 
                    {7, 8, 9, 10, 11, 12}, 
                    {13, 14, 15, 16, 17, 18} 
                    }; 
        spiralPrint(R,C,a); 
    } 
} 
  
// This code is contributed by Sam007 

PHP

<?php  
// PHP program to print a given 
// matrix in spiral form 
$R = 3; 
$C = 6; 
  
function spiralPrint($m, $n, &$a) 
{ 
    $k = 0; 
    $l = 0; 
  
    /* $k - starting row index 
        $m - ending row index 
        $l - starting column index 
        $n - ending column index 
        $i - iterator 
    */
  
    while ($k < $m && $l < $n) 
    { 
        /* Print the first row from 
           the remaining rows */
        for ($i = $l; $i < $n; ++$i) 
        { 
            echo $a[$k][$i] . " "; 
        } 
        $k++; 
  
        /* Print the last column  
        from the remaining columns */
        for ($i = $k; $i < $m; ++$i) 
        { 
            echo $a[$i][$n - 1] . " "; 
        } 
        $n--; 
  
        /* Print the last row from 
           the remaining rows */
        if ($k < $m) 
        { 
            for ($i = $n - 1; $i >= $l; --$i) 
            { 
                echo $a[$m - 1][$i] . " "; 
            } 
            $m--; 
        } 
  
        /* Print the first column from 
           the remaining columns */
        if ($l < $n) 
        { 
            for ($i = $m - 1; $i >= $k; --$i) 
            { 
                echo $a[$i][$l] . " "; 
            } 
            $l++;  
        }      
    } 
} 
  
// Driver code 
$a = array(array(1, 2, 3, 4, 5, 6), 
           array(7, 8, 9, 10, 11, 12), 
           array(13, 14, 15, 16, 17, 18)); 
  
spiralPrint($R, $C, $a); 
  
// This code is contributed 
// by ChitraNayal 
?> 

Output:

1 2 3 4 5 6 12 18 17 16 15 14 13 7 8 9 10 11

Time Complexity: Time complexity of the above solution is O(mn).

Please write comments if you find the above code incorrect, or find other ways to solve the same problem.

Print a given matrix in spiral form

C/C++

Java

Python3

C#

PHP

tags:

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