Kertoma

// Päättele luku x
// Kun saat tietoa kertomasta
 
const { createInterface } = require("readline")
const interface = createInterface({
    input: process.stdin,
    terminal: false
})
 
function findDigits(factorial) {
    let count = 0
    for (let i = 2; i <= factorial; i++) count += Math.log10(i)
    return Math.floor(count) + 1
}
function factorial(number) {
    let returnValue = 1n
    for (let i = 2n; i <= number; i++) returnValue *= i
    return returnValue  
}
function getCounts(string) {
    let counts = new Array(10).fill(0)
    for (const char of string.split("")) {
        if (isNaN(parseInt(char))) continue
        counts[parseInt(char)] += 1
    }
    return counts
}

 
const manualTarget = 100000
const fallbackThreshold = 1
 
interface.once("line", (line) => {
    const expectedCounts = line.split(" ")
        .map((val) => parseInt(val))
    
    // Find the expected length of the factorial and find a factorial within a range of lengths with a given precision
    const expectedLength = expectedCounts.reduce((a, b) => a + b)
    let currentTarget = [1, manualTarget]
    let lastTarget = []
    while(true) {
        // If the min factorial's length is more than the mean of the min-max factorial, add the mean as the min
        // and the other way around for if it's larger
        if (currentTarget[1] - currentTarget[0] < fallbackThreshold + (currentTarget[1] < 1000 ? 3 : 0)) break
        const newTarget = Math.round((currentTarget[1] + currentTarget[0]) / 2)
        const testFactorialLength = findDigits(newTarget)
        if (testFactorialLength === expectedLength && currentTarget[1] < 10000 ) break
        else if (testFactorialLength > expectedLength) currentTarget[1] = newTarget
        else currentTarget[0] = newTarget

        if (lastTarget === newTarget) break
        lastTarget = newTarget
    }

    if (currentTarget[0] !== currentTarget[1]) {
        let lastValue = factorial(BigInt(currentTarget[0]))
        let i = BigInt(currentTarget[0])
        while (i !== currentTarget[1]) {
            const calculatedCounts = getCounts(lastValue.toString())
            if (expectedCounts.join("") === calculatedCounts.join("")) {
                console.log(i.toString())
                break
            }
            ++i
            lastValue *= i
        }
    } else {
        console.log(currentTarget[0].toString())
    }
    process.exit()
})

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3

Verdict: ACCEPTED

Test 6

Group: 1, 2, 3

Verdict: ACCEPTED

Test 7

Group: 2, 3

Verdict: ACCEPTED

Test 8

Group: 2, 3

Verdict: ACCEPTED

Test 9

Group: 2, 3

Verdict: ACCEPTED

Test 10

Group: 2, 3

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 15

Group: 3

Verdict: WRONG ANSWER

Test 16

Group: 3

Verdict: WRONG ANSWER