Function to the find element at ( i , j ) index
int findInGrid ( int i , int j ) { if ( i == j ) return ( i * i - ( i - 1 ) ) ; else if ( i > j ) { if ( i % 2 == 0 ) return i * i - ( j - 1 ) ; else return ( i - 1 ) * ( i - 1 ) + 1 + ( j - 1 ) ; } else { if ( j % 2 == 0 ) return ( j - 1 ) * ( j - 1 ) + 1 + ( i - 1 ) ; else return j * j - ( i - 1 ) ; } }