A stack machine of commands in Rust
Rust interview exercise on Structs & Enums, difficulty 3 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Write run(commands) that executes commands against a stack of i32 and returns the final stack. Push(n) pushes; Pop discards the top; Add pops two values and pushes their sum; Dup pushes a copy of the top. When a command needs more values than the stack holds, return Err("stack underflow at command N") with the zero-based index.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.