### re: Daily Challenge #50 - Number Neighbor VIEW POST

any numbers ±1

🤔
Most people interpreted that as only a single number could vary at a time, others took the example too literally as the full number +- 1...

So I thought...

What if any numberS (plural) means any number of digits can vary...?

const neighbourSingle = (num) => [...new Set([ clamp(num-1), num, clamp(num+1) ])];
const clamp = (num) => Math.min(Math.max(num, 0), 9);
/*
neighbourSingle(5) === [4, 5, 6]
neighbourSingle(0) === [0, 1]
*/

const neighbours = (phoneString) => {
return phoneString.split("").reduce((a,b) => a.flatMap(c=> neighbourSingle(parseInt(b)).map(d=> c+d)) ,[""])
}
/*
neighbours("55")
(9) ["44", "45", "46", "54", "55", "56", "64", "65", "66"]

neighbours("555")
(27) ["444", "445", "446", "454", "455", "456", "464", "465", "466", "544", "545", "546", "554", "555", "556", "564", "565", "566", "644", "645", "646", "654", "655", "656", "664", "665", "666"]

neighbours("5555555555")
(59049) ["4444444444", "4444444445", "4444444446", "4444444454", "4444444455", "4444444456", "4444444464", "4444444465", "4444444466", "4444444544", "4444444545", "4444444546", "4444444554", "4444444555", "4444444556", "4444444564", "4444444565", "4444444566", "4444444644", "4444444645", "4444444646", "4444444654", "4444444655", "4444444656", "4444444664", "4444444665", "4444444666", "4444445444", "4444445445", "4444445446", "4444445454", "4444445455", "4444445456", "4444445464", "4444445465", "4444445466", "4444445544", "4444445545", "4444445546", "4444445554", "4444445555", "4444445556", "4444445564", "4444445565", "4444445566", "4444445644", "4444445645", "4444445646", "4444445654", "4444445655", "4444445656", "4444445664", "4444445665", "4444445666", "4444446444", "4444446445", "4444446446", "4444446454", "4444446455", "4444446456", "4444446464", "4444446465", "4444446466", "4444446544", "4444446545", "4444446546", "4444446554", "4444446555", "4444446556", "4444446564", "4444446565", "4444446566", "4444446644", "4444446645", "4444446646", "4444446654", "4444446655", "4444446656", "4444446664", "4444446665", "4444446666", "4444454444", "4444454445", "4444454446", "4444454454", "4444454455", "4444454456", "4444454464", "4444454465", "4444454466", "4444454544", "4444454545", "4444454546", "4444454554", "4444454555", "4444454556", "4444454564", "4444454565", "4444454566", "4444454644", …]
*/

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