Overview
Fibonacci sequence: 0, 1, 1, 2, 3, 5, 8, 13... — har number pichle do ka sum. Nature mein bhi milta hai yaar.
Analogy
Jaise rabbits multiply karte hain — har month pichle do months ke rabbits ka sum.
Step-by-step
- a, b = 0, 1 se start karo
- n times loop mein a, b = b, a+b
- Tuple unpacking: a, b = b, a+b ek saath update karta hai
- nth Fibonacci: n iterations ke baad a value hai
Visual
def fib(n):
a, b = 0, 1
for _ in range(n):
a, b = b, a + b
return a
fib(7) # 13
Common mistakes
- Ek ek karke update karna (a=b; b=a+b galat) — pehle a update hoga
- Off-by-one: fib(0)=0, fib(1)=1 sequence
- Large n ke liye integer overflow — Python mein nahi hota
Practice questions
- First 20 Fibonacci numbers print karo
- Check karo given number Fibonacci hai ya nahi