Assign values at desired place in the matrix
for ( int i = 0 ; i < n - 1 ; i ++ ) { matrix [ i ] [ u ] = i + 1 ; for ( int j = 1 ; j < n / 2 ; j ++ ) { int a = ( i + j ) % ( n - 1 ) ; int b = ( i - j + n - 1 ) % ( n - 1 ) ; if ( a < b ) swap ( a , b ) ; matrix [ b ] [ a ] = i + 1 ; } }