# 问题 大数和大数加法运算。 # 分析过程 - 输入：大数数据结构和加法运算。 - 输出：无 - 思路：见注释 # 解决方法 ```swift // A big number struct. Use [UInt8] struct BigNumber { // Only '0' ~ '9' var data: Array<UInt8> init(count: Int = 1) { data = Array<UInt8>.init(repeating: 0, count: count) } init(number: UInt) { data = Array<UInt8>.init(repeating: 0, count: "\(number)".count) var i = 0; for char in "\(number)" { guard let num = Int("\(char)") else { break } data[i] = UInt8(num) i += 1 } } func printSelf() { let str = data.reduce(into: "") { $0 = "\($0)\($1)" } print(str) } } // Big number plus func +(a: BigNumber, b: BigNumber) -> BigNumber { var a = a var b = b a.data.reverse() b.data.reverse() let countA = a.data.count let countB = b.data.count let countMax = max(countA, countB) let countMin = min(countA, countB) let biggerNumber = countA > countB ? a : b var result = BigNumber.init(count: countMax) var carryFlag = false for i in 0..<countMin { var sum = a.data[i] + b.data[i] sum += carryFlag ? 1 : 0 if sum >= 10 { sum = sum % 10 carryFlag = true } else { carryFlag = false } result.data[i] = sum } for i in countMin..<countMax { var sum = biggerNumber.data[i] sum += carryFlag ? 1 : 0 if sum >= 10 { sum = sum % 10 carryFlag = true } else { carryFlag = false } result.data[i] = sum } if carryFlag { result.data.append(1) } result.data.reverse() return result } ```