Medium data structure and algorithm practice puzzle.
Given how many tickets each person in line wants and a position k, return how many seconds until person k is done. Each second, the person at the front buys one ticket and goes to the back if they need more. Simulate the line: go around buying one ticket per person who still needs one, adding a second each time, until person k hits 0.
Solve it three ways: snap the jigsaw pieces together, fill in the blanks, or type it from scratch against the tests. This one is free.
Every line of the solution comes with a note explaining why it is there, and a step by step replay shows the code running. At level 3, where you type it yourself, you can ask for an AI mock interview on this problem that ends with a hiring manager's scorecard.
Then grow it into a real project with the Software Engineer button: this puzzle becomes the Ticket Stats Roll-up, a pipeline you can run and download. See every Software Engineer project.
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