This tool is designed to help you match up one or more receipts with a single reimbursement. This means you can easily keep track of receipts you have not yet reimbursed and audit your books.
Receipts are represented as negative values, and reimbursements as positive values. In general, the input should be a value in Dollars and Cents, some white space, and a description.
We are solving a special case of the zero-sum problem, which is NP-Complete; a class of problems that can be very hard. So, instead of trying to find every solution, we try to find the easiest solution. So if Dave has been reimbursed for $3 and there is a receipt for $3 of Carrots, we assume Dave's reimbursement was for the Carrots. We only consider the possibility that Dave's reimbursement could have been for multiple receipts if it couldn't have been for a single receipt.
If the tool is too slow, you can try simplifying the problem by finding reimbursements corresponding to many receipts and removing those receipts from the tool's input. Alternatively, you can download the tool and run it directly.