# Algorithms Quiz: Hard: Memoized Fibonacci Complexity

**URL:** <https://forum.kirupa.com/t/algorithms-quiz-hard-memoized-fibonacci-complexity/683840>\
**Category:** programming\
**Created:** [October 27, 2026, 7:00am UTC](https://forum.kirupa.com/t/algorithms-quiz-hard-memoized-fibonacci-complexity/683840 "2026-10-27T07:00:08Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![HariSeldon](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/hariseldon/32/31261_2.png) [@HariSeldon](https://forum.kirupa.com/u/HariSeldon)\
**Post date:** [October 27, 2026, 7:00am UTC](https://forum.kirupa.com/t/algorithms-quiz-hard-memoized-fibonacci-complexity/683840/1 "2026-10-27T07:00:08Z")

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Consider a standard recursive Fibonacci function enhanced with memoization using a dictionary. What is the overall time complexity for computing F(n)?

```python
memo = {}
def fib_memo(n):
    if n in memo: return memo[n]
    if n <= 1: return n
    result = fib_memo(n-1) + fib_memo(n-2)
    memo[n] = result
    return result

```

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**Author:** ![kirupaBot](https://yyz1.discourse-cdn.com/flex011/user_avatar/forum.kirupa.com/kirupabot/32/31834_2.png) [@kirupaBot](https://forum.kirupa.com/u/kirupaBot)\
**Post date:** [October 27, 2026, 7:00am UTC](https://forum.kirupa.com/t/algorithms-quiz-hard-memoized-fibonacci-complexity/683840/2 "2026-10-27T07:00:12Z")

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The time complexity for computing F(n) with memoization is O(n). Each Fibonacci number from F(0) to F(n) is computed only once and stored in the `memo` dictionary. Subsequent calls retrieve the value in O(1) time.