Step 4. Continue till completed. This is shown in figure 5.12. Solid lines show the routes that can be taken from 'a' to every other node. Evidently there are a number of alterative paths giving least cost. They are 40 20 80 20 10 f54 20 30 10 90 20 30 20 20 050 40 10 40 30 40 10 10 30 20 Fig. 5.12 0 ----- (involving 6 nodes), (11) -- (involving 5 nodes). (iii) - 84 (involving 7 nodes), (iv) ------ (involving 6 nodes), (v) a-d-8-1-k (involving 5 nodes), (W) ---- (involving 6 nodes), All the routes have the same cost (90) of travelling from 'a' to'k'. If, however, an additional constraint is imposed eg person is to visit minimum number of stations before reaching 'K', the number of alternative optimum (shortest) cost routes decreases to only two () ---- (11) ------- EXAMPLE 5.10-2 A person wishes to go from station a to destination i in the network shown in Fig. 5.13. The number on the links represent the cost of travelling from one node to another. Find the least cost route 27 18 30 21 15 19/36 30 24 ( 18 39 18 15 18 21 33 Fig. 5.13