Overview
Sliding window: array pe ek window slide karte karte best/max/min subarray find karo — O(n).
Analogy
Jaise train ki window se bahar dekho — window move hoti hai, view update hota hai.
Step-by-step
- Window bounds define karo (left, right)
- Window expand/shrink karo condition ke hisaab se
- Window mein aggregate maintain karo (sum, max, set)
- min/max window size ya score track karo
Visual
[2,1,5,1,3,2] k=3
[2,1,5]=8, [1,5,1]=7, [5,1,3]=9, [1,3,2]=6
Max sum = 9
Common mistakes
- Window shrink bhool jaana — window left pointer advance karo
- Fixed vs variable size window — problem statement padho
- Edge case: empty array ya k > array size
Practice questions
- Maximum sum subarray of size k nikalo
- Longest substring without repeating characters solve karo