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Kunal Singal's avatar

Okay suppose whole world is made of X San Francisco Bay areas which has Y road intersections.

So total nodes across the world map = X * Y

1. Without partitioning dijkstra time complexity of order (X*Y) log (X*Y)

2. With partitioning i am interacting with boundary nodes only for each partition.

So now, number of boundary nodes per partition = Y ^ 1/2 (as going area to perimeter)

and effective time complexity becomes of order (X * Y^1/2) log(X * Y^1/2)

Just to give an idea, lets take X = 10K, Y = 500, 000 (half million)

1. without paritioning time complexity of order ~ 5e9 (5 * 10 ^ 9)

2. with partitioning time complexity of order ~ 7e6

Doesn't sound much of an optimization assuming X can be very large as we are talking about the world here

Am i missing something here?

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