DevExCode

2648. Generate Fibonacci Sequence

Explanation

To generate the Fibonacci sequence, we can create a generator function that yields the Fibonacci numbers one by one. We can use a while loop inside the generator function to calculate the next Fibonacci number based on the previous two numbers. The generator function will keep track of the current and previous Fibonacci numbers.

Algorithm:

  1. Create a generator function fibGenerator that initializes prev and curr to 0 and 1 respectively.
  2. Yield the first Fibonacci number which is 0.
  3. Use a while loop that runs callCount times to generate the next Fibonacci numbers.
  4. Calculate the next Fibonacci number as the sum of prev and curr.
  5. Update prev and curr with the current values and yield the new Fibonacci number.
  6. Repeat steps 4-5 for callCount iterations.

Time Complexity:

The time complexity of generating the Fibonacci sequence is O(n), where n is the callCount.

Space Complexity:

The space complexity of the generator function is O(1) as we are only storing the previous and current Fibonacci numbers.

View Leetcode Problem
import java.util.Iterator;

public class FibonacciGenerator implements Iterator<Integer> {
    private int prev = 0;
    private int curr = 1;
    private int count = 0;
    
    @Override
    public boolean hasNext() {
        return true;
    }

    @Override
    public Integer next() {
        if (count == 0) {
            count++;
            return prev;
        }
        
        int next = prev + curr;
        prev = curr;
        curr = next;
        count++;
        
        return prev;
    }
}

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