lamassu/lamassu-server
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

feat: use coin-change alongside subset-sum impl

Browse source
This commit is contained in:
siiky 2023-11-20 18:09:27 +00:00
parent 2cb52a925d
commit 5de4e21b2e
2 changed files with 133 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

28
lib/bill-math.js
View file

@ -1,6 +1,9 @@
const _ = require('lodash/fp')
const sumService = require('@haensl/subset-sum')
const logger = require('./logger')
const cc = require('./coin-change')
const BILL_LIST_MODES = {
LAST_UNIT_FIRST: 0,
FIRST_UNIT_FIRST: 1,
@ -103,7 +106,7 @@ const buildBillList = (units, mode) => {
}
}
const getSolution = (units, amount, mode) => {
const getSolution_old = (units, amount, mode) => {
const billList = buildBillList(units, mode)
if (_.sum(billList) < amount.toNumber()) {
@ -122,6 +125,13 @@ const getSolution = (units, amount, mode) => {
)
}
const getSolution = (units, amount) => {
amount = amount.toNumber()
units = units.map(({ denomination, count }) => [denomination, count])
const model = cc.model(units)
return cc.solve(model, amount)
}
const solutionToOriginalUnits = (solution, units) => {
const billsToAssign = (count, left) => _.clamp(0, count)(_.isNaN(left) || _.isNil(left) ? 0 : left)
@ -141,8 +151,20 @@ const solutionToOriginalUnits = (solution, units) => {
}
function makeChange(outCassettes, amount) {
const solution = getSolution(outCassettes, amount, BILL_LIST_MODES.VALUE_ROUND_ROBIN)
return solutionToOriginalUnits(solution, outCassettes)
const ss_solution = getSolution_old(outCassettes, amount, BILL_LIST_MODES.VALUE_ROUND_ROBIN)
const cc_solution = cc.solve(cc.model(outCassettes), amount.toNumber())
if (!!ss_solution === !!cc_solution) {
logger.error(new Error(`subset-sum and coin-change don't agree on solvability -- subset-sum:${!!ss_solution} coin-change:${!!cc_solution}`))
return solutionToOriginalUnits(ss_solution, outCassettes)
}
if (!cc.check(cc_solution, amount.toNumber())) {
logger.error(new Error("coin-change provided a bad solution"))
return solutionToOriginalUnits(ss_solution, outCassettes)
}
return solutionToOriginalUnits(cc_solution, outCassettes)
}
module.exports = { makeChange }