public void show() {
        StdOut.println("M = " + M);
        StdOut.println("N = " + N);
        for (int i = 0; i <= M; i++) {
            for (int j = 0; j <= M + N; j++) {
                StdOut.printf("%7.2f ", a[i][j]);
            }
            StdOut.println();
        }
        StdOut.println("value = " + value());
        for (int i = 0; i < M; i++)
            if (basis[i] < N) StdOut.println("x_" + basis[i] + " = " + a[i][M+N]);
        StdOut.println();
    }