### Interview question which I faced during FAANG interview

Programming question given to me at leetcode.

Given two strings representing very large integer numbers ("123" , "30") return a string      representing the sum of the two numbers ("153").

The above question can be rephrased as:-

Add two numbers represented by strings

Sum of two large numbers

Add Two Very Large Number (out of range)

How to add two string numbers

#### Solution in Swift programming language:

func add(first: String, second: String) {

var input1 = first

var input2 = second

var firstArray = Array(first)

var secondArray = Array(second)

//both inputs should have same number of characters

var differenceOfCharacter = 0

if firstArray.count > secondArray.count {

differenceOfCharacter = firstArray.count - secondArray.count

(0..<differenceOfCharacter).forEach { (_) in

input2 = "0" + input2

}

} else {

differenceOfCharacter = secondArray.count - firstArray.count

(0..<differenceOfCharacter).forEach { (_) in

input1 = "0" + input1

}

}

firstArray = Array(input1)

secondArray = Array(input2)

var reminder = 0

var sum = 0

var sumString = ""

for (index,_) in firstArray.enumerated().reversed() {

let a = firstArray[index].wholeNumberValue ?? 0

let b = secondArray[index].wholeNumberValue ?? 0

sum = (a + b + reminder) % 10

reminder = (a + b) / 10

sumString = "\(sum)" + sumString

}

print(sumString)

}