Google and Meta both ask this. It tests whether you understand the BST property deeply, not just superficially. The common mistake is checking only immediate children. Interviewers want to see you catch this bug and fix it with the range-based approach. The in-order traversal alternative is clean. Knowing multiple approaches shows depth of understanding. Interviewers may ask: "Is there another way to solve this?"
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$ curl repovive.com/roadmaps/maang-interview-prep/trees-bst/validate-binary-search-tree-why-this-problem
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