Overview
BFS (Breadth-First Search) — graph ya tree mein level by level explore karta hai. Shortest path unweighted graph mein.
Analogy
Jaise pani mein stone daalo — rings outward expand hoti hain, pehle paas wale, phir door wale.
Step-by-step
- Source node queue mein daalo
- Queue se node nikalo, usse process karo
- Unvisited neighbors queue mein daalo, visited mark karo
- Queue empty hone tak repeat karo
Visual
Graph: 1-2, 1-3, 2-4, 3-5
BFS from 1: [1] -> [2,3] -> [4,5]
Common mistakes
- Visited set bhool jaana — infinite loop in cycles
- Enqueue karte time visited mark karo, dequeue pe nahi
- Source node visited mark karna bhool jaana
Practice questions
- BFS se shortest path unweighted graph mein nikalo
- Level order traversal binary tree mein karo