Step 3: for each node find the largest partition ID that it belongs to

step3.txt

-- Input:
part.	source	adjacency
ID	node	list
29	28	29,23
26	20	26,25,24,23,22,21

-- Create records:
source	node	partition
node
28	28	29
28	29	29
28	23	29
20	20	26
20	26	26
20	25	26
20	24	26
20	23	26
20	22	26
20	21	26

-- Group by node:
Group for node 28 =
28	28	29
Group for node 29 =
28	29	29
Group for node 23 (mind the ordering) =
28	23	29
20	23	26
Group for node 20 =
20	20	26
Remainder snipped...

-- Output:
source	node	partition
node
28	28	29
28	29	29
28	23	29
20	20	26
20	26	26
20	25	26
20	24	26
20	23	29     <=== THIS ONE GOT UPDATED FROM 26 to 29!
20	22	26
20	21	26