Level 3Exercise #73

Build graph adjacency

Convert directed edges into an adjacency-list dictionary.

What you’ll practice

This Level 3 exercise focuses on defaultdict graph in the Collections curriculum. Solve the challenge prompt above using clear, idiomatic Python and the relevant language or standard-library tools.

Relevant Python reference: collections.defaultdict.

Sample Test Cases

Example #1

Input:adjacency([('A','B'),('A','C')])

Output:{'A':['B','C']}

Reference Solution

Reveal Reference Solution

def adjacency(edges: list[tuple[str,str]]) -> dict[str,list[str]]:
    from collections import defaultdict
    graph = defaultdict(list)
    for source, target in edges:
        graph[source].append(target)
    return dict(graph)

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Build graph adjacency

What you’ll practice

Sample Test Cases

Further Reading

Reference Solution