The following is a tabular presentation of the Dijkstra SSAD algorithm trace 
from the Weighted Graph notes; x denotes infinity.


  a    b    c    d    e    f    g    h    i    Current solution set
----------------------------------------------------------------------------
  0   
add   15   25    x    x    x    x    x    x    {a}
     add   25    x   25    x    x   20   40    {a, b}
           25    x   25    x    x  add   35    {a, b, h}
          add   35   25    x    x        35    {a, b, h, c}
                35  add   35   30        35    {a, b, h, c, e}
                35        35  add        35    {a, b, h, c, e, g}
               add        35             35    {a, b, h, c, e, g, d}
                         add             35    {a, b, h, c, e, g, d, f}
                                        add    {a, b, h, c, e, g, d, f, i}
----------------------------------------------------------------------------

Solution:
Node        a    b    c    d    e    f    g    h    i
----------------------------------------------------------------------------
Distance    0   15   25   35   25   35   30   20   35
----------------------------------------------------------------------------