BeauNouvelle

let int1 = BigInt(value: "34757377374573285823949593499549646311234")  
let int2 = BigInt(value: "45123498348958923845838948528381283721377123454345")  
let product = int1 * int2  
// result: 1568374460575699918065222772187576926314538959488859994856690985365041943440429553059611730

BeauNouvelle

import UIKit
import Foundation

struct BigInt {
    
    var value: String
    
    func multiply(right: BigInt) -> BigInt {
        var leftCharacterArray = value.characters.reversed().map { Int(String($0))! }
        var rightCharacterArray = right.value.characters.reversed().map { Int(String($0))! }

BeauNouvelle

func * (left: BigInt, right: BigInt) -> BigInt { return left.multiply(right) }

BeauNouvelle

func multiply(right: BigInt) -> BigInt {

    var a1 = value.characters.reversed().map { Int(String($0))! }
    var a2 = right.value.characters.reversed().map { Int(String($0))! }
    ...
    ...

    // And change the last line
    return BigInt(value: result.map { String($0) }.joined(separator: ""))
}

BeauNouvelle

struct BigInt {

    var value: String

    func multiply(right: String) -> String {
        // We'll change this line to use `value`
        var leftCharacterArray = value.characters.reversed().map { Int(String($0))! }
        var rightCharacterArray = right.characters.reversed().map { Int(String($0))! }
    ...

BeauNouvelle

let int1 = BigInt("10")  
let int2 = BigInt("5")  
let product = int1 * int2  

BeauNouvelle

func multiply(left: String, right: String) -> String {
    var leftCharacterArray = left.characters.reversed().map { Int(String($0))! }
    var rightCharacterArray = right.characters.reversed().map { Int(String($0))! }
    var result = [Int](repeating: 0, count: leftCharacterArray.count+rightCharacterArray.count)
    
    for leftIndex in 0..<leftCharacterArray.count {
        for rightIndex in 0..<rightCharacterArray.count {
            
            let resultIndex = leftIndex + rightIndex
            

BeauNouvelle

struct BigInt {  
    var value: String
}