How do you solve Generate Fibonacci Sequence on LeetCode?

Generate Fibonacci Sequence (LeetCode #2648) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(1) space complexity. Key insight: Understanding the difference between recursive and iterative solutions is crucial.

What is the time complexity of Generate Fibonacci Sequence?

The optimal solution for Generate Fibonacci Sequence runs in O(n) time and uses O(1) space. This complexity is linear because we only loop through the numbers once, calculating each Fibonacci number in constant time.

What is the brute force solution for Generate Fibonacci Sequence?

The brute force approach for Generate Fibonacci Sequence is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute-force approach involves calculating each Fibonacci number recursively. This method is straightforward but inefficient due to repeated calculations. The optimal Optimal Solution approach improves this to O(n).

What are the interview tips for Generate Fibonacci Sequence?

Explain your thought process clearly while coding. Discuss the time and space complexities of your solution. Be prepared to optimize your solution if asked.

What are common mistakes when solving Generate Fibonacci Sequence?

Forgetting to yield values in the generator function. Using recursion without understanding the implications on performance.

#2648

Generate Fibonacci Sequence

Easy

Two PointersDynamic Programming

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(1)

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Intuition

Time O(n)Space O(1)

The optimal solution uses an iterative approach to generate Fibonacci numbers, which avoids the overhead of recursion and repeated calculations.

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Algorithm

3 steps

1Step 1: Initialize two variables to store the first two Fibonacci numbers.
2Step 2: Use a loop to yield the Fibonacci numbers up to callCount.
3Step 3: Update the variables in each iteration to get the next Fibonacci number.

solution.py5 lines

1def fib_generator(call_count):
2    a, b = 0, 1
3    for _ in range(call_count):
4        yield a
5        a, b = b, a + b

ℹ

Complexity note: This complexity is linear because we only loop through the numbers once, calculating each Fibonacci number in constant time.

1Understanding the difference between recursive and iterative solutions is crucial.
2Generators allow for efficient memory usage by yielding values one at a time.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.