CODE CHALLENGE

QUESTION-

For a given odd number N, find out the matrix that contains elements from 1 to N 2. This matrix should satisfy the following conditions :

• Each number can occur only once in the matrix.
• The sum of all the rows, columns and diagonals must be equal.

For example,  If N=3 then matrix will be 

8  1  6
3  5  7
4  9  2

Here in the above matrix, the sum of all the rows, columns and diagonals will be 15.

Input Format: 
Input contains a single positive odd integer N where N <=20.


Output Format:
The output contains the matrix that satisfies the given conditions. If the value of N is even, print "INVALID".


Input Sample 1:
5
Output Sample 1:
17   24    1     8     15
23     5     7    14   16
 4      6    13   20   22
10   12   19   21    3
11   18    25   2      9

Input Sample 2:
8
Output Sample 2:
INVALID 

CODE-

#include<stdio.h>
#include<string.h>

// A function to generate odd sized magic squares
void generateSquare(int n)
{
    int magicSquare[n][n];

    // set all slots as 0
    memset(magicSquare, 0, sizeof(magicSquare));

    // Initialize position for 1
    int i = n/2;
    int j = n-1;

    // One by one put all values in magic square
    for (int num=1; num <= n*n; )
    {
        if (i==-1 && j==n) //3rd condition
        {
            j = n-2;
            i = 0;
        }
        else        {
            // 1st condition helper if next number
            // goes to out of square's right side
            if (j == n)
                j = 0;

            // 1st condition helper if next number
            // is goes to out of square's upper side
            if (i < 0)
                i=n-1;
        }
        if (magicSquare[i][j]) //2nd condition
        {
            j -= 2;
            i++;
            continue;
        }
        else            magicSquare[i][j] = num++; //set number

        j++; i--; //1st condition
    }

    // Print magic square
    printf("The Magic Square for n=%d:\nSum of "       "each row or column %d:\n\n",  n, n*(n*n+1)/2);

    for (i=n-1; i>=0; i--)
    {
        for (j=n-1; j>=0; j--)
            printf("%3d ", magicSquare[j][i]);
        printf("\n");
    }
}

int main()
{
    int n;  // Works only when n is odd
    scanf("%d",&n); 

   if(n%2==0)    

printf("invalid");    

else   

  generateSquare (n); 

    return 0;
} 

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