# Print a given matrix in reverse spiral form in C++

In this problem, we are given a 2-dimensional matrix. Our task is to print all the elements of the matrix in reverse spiral form.

Let’s take an example to understand the problem

Input:
12 23 54 67
76 90 01 51
43 18 49 5
31 91 75 9
Output: 18 49 1 90 76 43 31 91 75 9 5 51 67 54 23 12

We will start from the center of the matrix and print elements in reverse spiral direction taking four loops for printing elements in reverse direction.

## Example

Program to show the implementation of our solution

Live Demo

#include <iostream>
#define R 3
#define C 6
using namespace std;
void printReverseSpiral(int m, int n, int a[R][C]) {
long int b[100];
int i, k = 0, l = 0;
int z = 0;
int size = m*n;
while (k < m && l < n) {
int val;
for (i = l; i < n; ++i){
val = a[k][i];
b[z] = val;
++z;
}
k++;
for (i = k; i < m; ++i){
val = a[i][n-1];
b[z] = val;
++z;
}
n--;
if ( k < m){
for (i = n-1; i >= l; --i){
val = a[m-1][i];
b[z] = val;
++z;
}
m--;
}
if (l < n){
for (i = m-1; i >= k; --i){
val = a[i][l];
b[z] = val;
++z;
}
l++;
}
}
for (int i=size-1 ; i>=0 ; --i){
cout<<b[i]<<" ";
}
}
int main() {
int mat[R][C] = {
{34, 5, 6, 98, 12, 23},
{9, 12, 56, 87, 99, 1},
{13, 91, 50, 8, 21, 2}
};
cout<<"Printing reverse Spiral of the matrix :\n";
printReverseSpiral(R, C, mat);
return 0;
}

## Output

Printing reverse Spiral of the matrix −

99 87 56 12 9 13 91 50 8 21 2 1 23 12 98 6 5 34