Day 17/365: Sliding Window -- Variable -- DSA & System Design

365 Day DSA & System Design Challenge

Day 17 was about making adaptive windows feel logical.

What I wanted clear today:

• variable windows move because of a condition, not a preset width
• longest-substring problems shrink to repair invalidity
• minimum-window problems shrink after the target is satisfied
• the state inside the window is as important as the pointers
• pointer moves get easier once the exact condition is named

The biggest shift was realizing that variable-window problems are really negotiations with a rule. If I can say what makes the window invalid or sufficient, then I can explain why the left edge moves and why the right edge keeps expanding.

That also gave me a cleaner review habit: write down the exact condition first, then the pointer moves usually stop looking random.

That made Day 17 feel much more manageable than the old template version of this topic.

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Day 17/365 of the 365 Day DSA & System Design Challenge.