What is the Load Factor? How does it trigger a Rehash/Resize?

Difficulty: 5/10

load factor, rehashing, resize strategy

Load Factor and Resizing

The load factor measures how full a Hash Table is. For a table with n stored entries and m buckets, the load factor is alpha = n / m. As the load factor increases, collisions generally become more frequent, so implementations resize the table when a configured threshold is exceeded.

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A lower load factor generally means fewer collisions but more memory usage.
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A higher load factor improves memory efficiency but can increase lookup cost.
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Resizing usually allocates a larger table.
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Existing entries must be rehashed because bucket indexes depend on table capacity.
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A resize operation itself can take O(n).
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Over many insertions, resizing can still preserve amortized O(1) insertion.

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0-2 years experience

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