提出 #20355912

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ソースコード 拡げる

func readInt1(line: Int = #line, file: String = #file) -> Int {
    guard let string = readLine() else {
        preconditionFailure("No input (at line \(line) in \(file))")
    }
    guard let value = Int(string) else {
        preconditionFailure("Illegal input value: \(string) (at line \(line) in \(file))")
    }
    return value
}

enum LessThanOrEqualToElement {}
func <=(lhs: LessThanOrEqualToElement, rhs: LessThanOrEqualToElement) {}
extension RandomAccessCollection where Index == Int {
    func values(_: (LessThanOrEqualToElement, LessThanOrEqualToElement) -> (), _ predicate: (Element) throws -> Bool) rethrows -> SubSequence {
        var low = startIndex - 1
        var high = endIndex
        while high - low > 1 {
            let mid = low + (high - low) / 2
            if try predicate(self[mid]) {
                low = mid
            } else {
                high = mid
            }
        }
        return self[..<high]
    }
}

infix operator +?: AdditionPrecedence
extension FixedWidthInteger {
    static func +? (lhs: Self, rhs: Self) -> Self? {
        let (result, overflows) = lhs.addingReportingOverflow(rhs)
        if overflows { return nil }
        return result
    }
}

infix operator *?: MultiplicationPrecedence
extension FixedWidthInteger {
    static func *? (lhs: Self, rhs: Self) -> Self? {
        let (result, overflows) = lhs.multipliedReportingOverflow(by: rhs)
        if overflows { return nil }
        return result
    }
}

infix operator ..<?: RangeFormationPrecedence
func ..<?<T>(lhs: T, rhs: T) -> Range<T>? where T: Comparable {
    guard lhs <= rhs else { return nil }
    return lhs ..< rhs
}

func isXLessThanOrEqualToM(x: String, m: Int, radix n: Int) -> Bool {
    var v = 0
    var k = 1
    var overflows = false
    for d in x.reversed() {
        if overflows { return false }
        guard let dv = Int(String(d))! *? k else { return false }
        guard let newV = v +? dv else { return false }
        v = newV
        if v > m { return false }
        if let newK = k *? n {
            k = newK
        } else {
            overflows = true
        }
    }
    return true
}

let x = readLine()!
let m = readInt1()

let d = Int(String(x.max()!))!

if x.count == 1 {
    if d > m {
        print(0)
    } else {
        print(1)
    }
} else {
    if let range = (d + 1) ..<? (m + 1) {
        let nn = range.values(<=) { n in isXLessThanOrEqualToM(x: x, m: m, radix: n) }
        print(nn.count)
    } else {
        print(0)
    }
}

提出情報

ジャッジ結果