Valid Parentheses (LC #20) is one of Meta's most common screening questions. Push opening brackets onto the stack. When you see a closing bracket, check if it matches the stack top. If yes, pop. If no or stack is empty, return false. After processing all characters, the stack should be empty. This runs in time and space. The stack's LIFO property naturally handles nested structures by matching innermost brackets first. Meta uses this as a warm-up before harder problems.
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$ curl repovive.com/roadmaps/meta-interview-prep/stacks-queues/valid-parentheses
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