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Form coils in a matrix
  • Difficulty Level : Medium
  • Last Updated : 20 Mar, 2020

Given a positive integer n that represents dimensions of a 4n x 4n matrix with values from 1 to n filled from left to right and top to bottom. Form two coils from matrix and print the coils.

Examples:

Input  : n = 1;
Output : Coil 1 : 10 6 2 3 4 8 12 16 
         Coil 2 : 7 11 15 14 13 9 5 1
Explanation : Matrix is 
1  2  3  4 
5  6  7  8 
9  10 11 12 
13 14 15 16

Input  : n = 2;
Output : Coil 1 : 36 28 20 21 22 30 38 46 54 
                  53 52 51 50 42 34 26 18 10 
                  2 3 4 5 6 7 8 16 24 32 40 
                  48 56 64 
        Coil 2 : 29 37 45 44 43 35 27 19 11 12 
                 13 14 15 23 31 39 47 55 63 62 
                 61 60 59 58 57 49 41 33 25 17
                 9 1 
matrixcoil

Total elements in matrix are 16n2. All elements are divided in two coils. Every coil has 8n2 elements. We make two arrays of this size. We first fill elements in coil1 by traversing in given order. Once we have filled elements in coil1, we can get elements of other coil2 using formula coil2[i] = 16*n*n + 1 -coil1[i].

C++




// C++ program to print 2 coils of a
// 4n x 4n matrix.
#include<iostream>
using namespace std;
  
// Print coils in a matrix of size 4n x 4n 
void printCoils(int n)
{
    // Number of elements in each coil
    int m = 8*n*n;
  
    // Let us fill elements in coil 1.
    int coil1[m];
  
    // First element of coil1
    // 4*n*2*n + 2*n;
    coil1[0] = 8*n*n + 2*n;
    int curr = coil1[0];
  
    int nflg = 1, step = 2;
  
    // Fill remaining m-1 elements in coil1[]
    int index = 1;
    while (index < m)
    {
        // Fill elements of current step from
        // down to up
        for (int i=0; i<step; i++)
        {
            // Next element from current element
            curr = coil1[index++] = (curr - 4*n*nflg);
            if (index >= m)
                break;
        }
        if (index >= m)
            break;
  
        // Fill elements of current step from
        // up to down.
        for (int i=0; i<step; i++)
        {
            curr = coil1[index++] = curr + nflg;
            if (index >= m)
                break;
        }
        nflg = nflg*(-1);
        step += 2;
    }
  
    /* get coil2 from coil1 */
    int coil2[m];
    for (int i=0; i<8*n*n; i++)
        coil2[i] = 16*n*n + 1 -coil1[i];
  
    // Print both coils
    cout << "Coil 1 : ";
    for(int i=0; i<8*n*n; i++)
        cout << coil1[i] << " ";
    cout << "\nCoil 2 : ";
    for (int i=0; i<8*n*n; i++)
        cout << coil2[i] << " ";
}
  
// Driver code
int main()
{
    int n = 1;
    printCoils(n);
    return 0;
}

Java




// Java program to print 2 coils 
// of a 4n x 4n matrix.
  
class GFG {
      
    // Print coils in a matrix of size 4n x 4n
    static void printCoils(int n) 
    {
        // Number of elements in each coil
        int m = 8 * n * n;
      
        // Let us fill elements in coil 1.
        int coil1[] = new int[m];
      
        // First element of coil1
        // 4*n*2*n + 2*n;
        coil1[0] = 8 * n * n + 2 * n;
        int curr = coil1[0];
      
        int nflg = 1, step = 2;
      
        // Fill remaining m-1 elements in coil1[]
        int index = 1;
        while (index < m)
        {
            // Fill elements of current step from
            // down to up
            for (int i = 0; i < step; i++) 
                {
                    // Next element from current element
                    curr = coil1[index++] = (curr - 4 * n * nflg);
                    if (index >= m)
                    break;
                }
            if (index >= m)
                break;
          
            // Fill elements of current step from
            // up to down.
            for (int i = 0; i < step; i++) 
            {
                curr = coil1[index++] = curr + nflg;
                if (index >= m)
                break;
            }
              
            nflg = nflg * (-1);
            step += 2;
        }
      
        /* get coil2 from coil1 */
        int coil2[] = new int[m];
        for (int i = 0; i < 8 * n * n; i++)
            coil2[i] = 16 * n * n + 1 - coil1[i];
      
        // Print both coils
        System.out.print("Coil 1 : ");
          
        for (int i = 0; i < 8 * n * n; i++)
            System.out.print(coil1[i] + " ");
          
        System.out.print("\nCoil 2 : ");
          
        for (int i = 0; i < 8 * n * n; i++)
            System.out.print(coil2[i] + " ");
    }
      
    // Driver code
    public static void main(String[] args)
    {
        int n = 1;
        printCoils(n);
    }
}
  
// This code is contributed by Anant Agarwal.

Python3




# Python3 program to pr2 coils of a
# 4n x 4n matrix.
  
# Prcoils in a matrix of size 4n x 4n 
def printCoils(n):
      
    # Number of elements in each coil
    m = 8*n*n
      
    # Let us fill elements in coil 1.
    coil1 = [0]*m
      
    # First element of coil1
    # 4*n*2*n + 2*n
    coil1[0] = 8*n*n + 2*n
      
    curr = coil1[0]
      
    nflg = 1
    step = 2
      
    # Fill remaining m-1 elements in coil1[]
    index = 1
    while (index < m):
          
        # Fill elements of current step from
        # down to up
        for i in range(step):
              
            # Next element from current element
            curr = coil1[index] = (curr - 4*n*nflg)
            index += 1
            if (index >= m):
                break
        if (index >= m):
            break
          
        # Fill elements of current step from
        # up to down.
        for i in range(step):
              
            curr = coil1[index] = curr + nflg
            index += 1
            if (index >= m):
                break
        nflg = nflg*(-1)
        step += 2
      
    #get coil2 from coil1 */
      
    coil2 = [0]*m
    i = 0
    while(i < 8*n*n):
        coil2[i] = 16*n*n + 1 -coil1[i]
        i += 1
    # Prboth coils
    print("Coil 1 :", end = " ")
    i = 0
    while(i < 8*n*n):
        print(coil1[i], end = " ")
        i += 1
    print("\nCoil 2 :", end = " ")
    i = 0
    while(i < 8*n*n):
        print(coil2[i], end = " ")
        i += 1
  
# Driver code
  
n = 1
printCoils(n)
  
# This code is contributed by shubhamsingh10

C#




// C# program to print 2 coils 
// of a 4n x 4n matrix.
using System;
  
class GFG {
      
    // Print coils in a matrix of
    // size 4n x 4n
    static void printCoils(int n) 
    {
          
        // Number of elements in
        // each coil
        int m = 8 * n * n;
      
        // Let us fill elements in
        // coil 1.
        int [] coil1 = new int[m];
      
        // First element of coil1
        // 4*n*2*n + 2*n;
        coil1[0] = 8 * n * n + 2 * n;
        int curr = coil1[0];
      
        int nflg = 1, step = 2;
      
        // Fill remaining m-1 elements
        // in coil1[]
        int index = 1;
        while (index < m)
        {
              
            // Fill elements of current
            // step from down to up
            for (int i = 0; i < step; i++) 
                {
                    // Next element from 
                    // current element
                    curr = coil1[index++] 
                    = (curr - 4 * n * nflg);
                      
                    if (index >= m)
                        break;
                }
                  
            if (index >= m)
                break;
          
            // Fill elements of current step
            // from up to down.
            for (int i = 0; i < step; i++) 
            {
                curr = coil1[index++] = curr 
                                     + nflg;
                if (index >= m)
                    break;
            }
              
            nflg = nflg * (-1);
            step += 2;
        }
      
        /* get coil2 from coil1 */
        int [] coil2 = new int[m];
          
        for (int i = 0; i < 8 * n * n; i++)
            coil2[i] = 16 * n * n + 1 - coil1[i];
      
        // Print both coils
        Console.Write("Coil 1 : ");
          
        for (int i = 0; i < 8 * n * n; i++)
            Console.Write(coil1[i] + " ");
          
        Console.Write("\nCoil 2 : ");
          
        for (int i = 0; i < 8 * n * n; i++)
            Console.Write(coil2[i] + " ");
    }
      
    // Driver code
    public static void Main()
    {
        int n = 1;
          
        printCoils(n);
    }
}
  
// This code is contributed by KRV.

PHP




<?php
// PHP program to print 2 coils of a
// 4n x 4n matrix.
  
// Print coils in a matrix of size 4n x 4n 
function printCoils( $n)
{
      
    // Number of elements in each coil
    $m = 8 * $n * $n;
  
    // Let us fill elements in coil 1.
    $coil1 = array();
  
    // First element of coil1
    // 4*n*2*n + 2*n;
    $coil1[0] = 8 * $n * $n + 2 * $n;
    $curr = $coil1[0];
  
    $nflg = 1; $step = 2;
  
    // Fill remaining m-1 elements in coil1[]
    $index = 1;
    while ($index < $m)
    {
        // Fill elements of current step from
        // down to up
        for ( $i = 0; $i < $step; $i++)
        {
            // Next element from current element
            $curr = $coil1[$index++] = 
                     ($curr - 4*$n*$nflg);
            if ($index >= $m)
                break;
        }
        if ($index >= $m)
            break;
  
        // Fill elements of current step from
        // up to down.
        for ( $i=0; $i<$step; $i++)
        {
            $curr = $coil1[$index++] = 
                            $curr + $nflg;
            if ($index >= $m)
                break;
        }
        $nflg = $nflg * (-1);
        $step += 2;
    }
  
    /* get coil2 from coil1 */
    $coil2 = array();
      
    for ( $i = 0; $i < 8 * $n * $n; $i++)
        $coil2[$i] = 16 * $n * $n + 1 -$coil1[$i];
  
    // Print both coils
    echo "Coil 1 : ";
    for( $i = 0; $i < 8 * $n * $n; $i++)
    echo $coil1[$i] , " ";
      
    echo "\nCoil 2 : ";
    for ( $i = 0; $i < 8 * $n * $n; $i++)
        echo $coil2[$i] , " ";
}
  
// Driver code
$n = 1;
printCoils($n);
  
// This code is contributed by anuj_67.
?>


Output:



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

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This article is contributed by Roshni Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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