Akash's Notebook Match

Notebooks fall one at a time. Turn each one till the right label faces down, and see which ones your stock list has no room for.

Who this is for

Akash Kalbande runs a stationery shop in Sitabuldi, Nagpur, twenty steps from a school gate. In the last week of May he has eleven hundred notebooks stacked chest high in the back room, four brands, seven rulings, prices from 28 to 96 rupees. His diary says he has 40 four-line 76-page books. The shelf says 34. He has counted that stack three times since Tuesday and got a different answer twice.

How the job is done today

The diary sits under the counter. Akash writes each delivery in it in pencil, and crosses off sales at night when he remembers. His nephew Ronit counts the shelf on Sunday mornings and shouts the numbers across the shop while Akash ticks. Half the time a stack of single-line 172-page books is wearing a four-line label because a customer put it back wrong. So the two records disagree, and there is no way to tell which one is lying. He recounts. The distributor's man is on WhatsApp asking for the June order, and Akash guesses.

The screens, in order

1. What you have — Akash types in the kinds of notebooks he stocks and the two numbers for each one, what the diary says and what the shelf says, and nothing else happens yet.
2. The drop — Notebooks fall down the screen one after another, and tapping turns the notebook so a different side faces down, which is the only thing you can do here.
3. The shelf — The bottom of the same screen holds one slot for every kind of notebook the diary claims to have, and each notebook lands in whichever slot its facing-down side matches.
4. The leftovers — When the round ends this shows the notebooks that found no slot and the slots that stayed empty, which is exactly where the diary and the shelf disagree.
5. Which one was right — For each disagreement Akash picks the true number, and the diary gets corrected without anyone going back to count the stack again.

What it keeps track of

• Notebook kinds — brand, how many pages, what ruling, price
• The two counts — what the diary says, what the shelf says, when each was last checked
• A round — which day, which notebooks landed, which found no slot, which slots stayed empty
• Fixes — which kind, old number, new number, who decided

The one decision that matters

A notebook lands in the wrong slot. Does the round end there, or does it just sit in a leftover pile and the next one falls? Ending the round is the ordinary game answer and it makes the tapping tense. But the leftover pile is the whole reason this thing exists. Every notebook with nowhere to go is a real disagreement between the diary and the shelf, and Akash needs to see all of them in one go, not the first one. So no game over. Wrong drops stack up at the side, the round runs till the last notebook falls, and the pile at the end is the list of things to check. Speed can come from how fast the next one drops, not from punishment.

What to leave out of the first version

Leave out sales. Do not let the app touch the day's billing, do not have it subtract a notebook when one is sold. That turns it into shop software Akash has to feed every evening, and he will stop after four days. The first version only ever compares two numbers he already keeps. It should be openable in a spare five minutes and closable with nothing owed.

How you would know it worked

Ronit plays a round on his own on a Thursday evening without being asked to count anything. The next morning the diary line for four-line 76-page books gets changed from 40 to 34 in pencil, and nobody goes to the back room to recount the stack.

Build it

Paste this in and let it run.

I run a stationery shop near a school in Nagpur and my stock diary never agrees with what is actually on the shelf. Make me a small phone game where I first put in my notebook kinds, like Classmate 172 pages single line, with the number my diary says and the number I counted. Then notebooks fall down the screen one by one and each side of the notebook shows a different label, and the only thing I can do is tap to turn it so the correct label faces down and it drops into the matching slot at the bottom. Wrong ones should pile up at the side instead of ending the game. At the end show me every notebook that had no slot and every slot that stayed empty, and let me pick which number was right so my diary gets corrected. My nephew should want to play it.