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easyBlind 75
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This is a stack/invariant problem: once your stack represents the right thing, the rest is routine. It's a great warm-up that builds stack invariants without a ton of moving parts. Keep the stack invariant explicit; if it breaks, everything downstream breaks too.
StackString
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Meet Allison & Tim
Your AI coaches
Practice coding interviews out loud with real-time voice coaching. Your code actually runs.
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1Valid Parentheseseasy
2Part 2
3Part 3
Start Part 1 to unlock your next challenge
Based onLeetCode
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