Input  : 2
Output : 1 0
         0 1

Input :  4
Output : 1 0 0 0
         0 1 0 0
         0 0 1 0
         0 0 0 1
The explanation is simple. We need to make all
the elements of principal or main diagonal as 
1 and everything else as 0.

// C program to print Identity Matrix
#include<stdio.h>
 
int Identity(int num)
{
    int row, col;
     
    for (row = 0; row < num; row++)
    {
        for (col = 0; col < num; col++)
        {
            // Checking if row is equal to column
            if (row == col)
                printf("%d ", 1);
            else
                printf("%d ", 0);
        }
        printf("\n");
    }
    return 0;
}
 
// Driver Code
int main()
{
    int size = 5;
    identity(size);
    return 0;
}

1  0  0  0  0  
0  1  0  0  0  
0  0  1  0  0  
0  0  0  1  0  
0  0  0  0  1