Reference library

Dictionaries & sets

Key–value maps, uniqueness, counting, grouping, and fast lookups.

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Dictionaries & sets easy

Build adjacency dict graph from edges in Python

Convert a list of edges into an undirected adjacency dictionary, mapping each node to its neighbors, with sorted output.

graph adjacency dictionary
Python 
def build_adjacency_dict(edges):
    graph = {}
    for u, v in edges:
        if u not in graph:
            graph[u] = []
        if v not in graph:
            graph[v] = []
        graph[u].append(v)
        graph[v].append(u)
    return graph

if __name__ == "__main__":
    edges = [(1, 2), (2, 3), (3, 4), (4, 1)…
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