  N5----8-----N4
      </pre>
    </p>

    <p>
      Using "Inf" to indicate that there is no link between two nodes,
      the distance matrix for this graph is:
      <pre>
          0   40   15  Inf  Inf  Inf
         40    0   20   10   25    6
         15   20    0  100  Inf  Inf
        Inf   10  100    0  Inf  Inf
        Inf   25  Inf  Inf    0    8
        Inf    6  Inf  Inf    8    0
      </pre>
    </p>

    <p>
      Dijkstra's algorithm efficiently determines the length of the shortest
      