3.swift

import Foundation

func solution(_ n: Int) -> Int {

	func fac(_ n: Int) -> Int {
		if n == 1 {
			return 1
		}
		return (1...n).reduce(1, *)
	}

	let strN = "\(n)"
	let digitCount = strN.count
	if digitCount == 1 {
		return 1
	}
	var charMap = [Character: Int]()
	for i in strN {
		charMap[i] = (charMap[i] ?? 0) + 1
	}
	var total = charMap.reduce(fac(digitCount)) { (l, r) in
		return l / fac(r.value)
	}
	if let zeroCount = charMap["0"] {
		let count = zeroCount - 1
		var excludeCharMap = charMap
		if count == 0 {
			excludeCharMap.removeValue(forKey: "0")
		} else {
			excludeCharMap["0"] = count
		}
		let exclude = excludeCharMap.reduce(fac(digitCount - 1)) { (l, r) in
			return l / fac(r.value)
		}
		total = total - exclude
	}
	return total
}

func test(_ n: Int) {
	print("\(n) \(solution(n))")
}

test(0)
test(1)
test(2)
test(100)
test(123)
test(1132)
test(99998)