26 lines
1.0 KiB
Markdown
26 lines
1.0 KiB
Markdown
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The last data-structure we are going to cover is the graph.
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It is similar to a tree. In fact a tree is a special case
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of a graph, because a graph is also allowed to have circles,
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nodes that have a path to them self.
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Graphs are useful data-structure to encode relations.
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For example a road-network or friendships.
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To encode the most basic graphs you need two things.
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A list of nodes, sometimes called vertices, and a list of edges.
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The nodes represent objects and the edges represent their relation.
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For example you could have a graph of a road-network, where every
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intersection is a node and every street is an edge.
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With the edges and nodes you could encode more information, to use in your
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algorithm. So the intersections could have an GPS-position and the street
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some kind of cost, which indicates the amount of time you need to get to the
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other side.
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In this task we provided you with a very simplistic graph,
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which encodes the relationship between two people.
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Your task is to find out, who likes one, which likes them back.
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