The Gate Keeper

A easy Python interview practice problem on DataDriven. Write and execute real python code with instant grading.

Domain

Python

Difficulty

easy

Seniority

L4

Problem

An expression validator receives short strings built only from the bracket characters `()[]{}` and has to confirm each one is well-formed before it moves downstream. A string is valid when every opening bracket is closed by one of the same type in the correct order with nothing left open, so `([)]` fails even though the counts balance; an empty string counts as valid.

Summary

Not all openings have a closing.

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