Suppose we have one undirected star graph with n nodes labeled from 1 to n. As we know a star graph is a graph where there is one center node and exactly n - 1 edges that connect the center node with every other node. We have to find the center of the given star graph.
So, if the input is like
then the output will be 3 as 3 is at center.
To solve this, we will follow these steps −
seen := a new set
for each edge (u,v) in graph, do
if u is in seen, then
return u
if v is in seen, then
return v
insert u into seen
insert v into seen
Example
Let us see the following implementation to get better understanding −
def solve(graph):
seen = set()
for u,v in graph:
if u in seen:
return u
if v in seen:
return v
seen.add(u)
seen.add(v)
graph = [(1,3),(2,3),(4,3),(5,3),(6,3)]
print(solve(graph))Input
[(1,3),(2,3),(4,3),(5,3),(6,3)]
Output
3