415_Add_Strings

Author: Partho Biswas

README.md

@@ -243,6 +243,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |39| [350. Intersection of Two Arrays II](https://tinyurl.com/y9kdrubz) | [Python](https://tinyurl.com/wu6rdaw/350_Intersection_of_Two_Arrays_II.py), [Swift](https://tinyurl.com/wuja3c4/350_Intersection_of_Two_Arrays_II.swift) | --- | Easy | Check the follow-ups |
 |40| **[249. Group Shifted Strings](https://tinyurl.com/jsfd4l3)** | [Python](https://tinyurl.com/wu6rdaw/249_Group_Shifted_Strings.py), [Swift](https://tinyurl.com/wuja3c4/249_Group_Shifted_Strings.swift) | [Art 1](https://tinyurl.com/yd4ckev2) | Medium | Tricky one |
 |41| **[158. Read N Characters Given Read4 II - Call multiple times](https://tinyurl.com/y6snjozr)** | [Python](https://tinyurl.com/wu6rdaw/158_Read_N_Characters_Given_Read4_II_Call_multiple_times.py), [Swift](https://tinyurl.com/wuja3c4/158_Read_N_Characters_Given_Read4_II_Call_multiple_times.swift) | [Art 1](https://tinyurl.com/y5qu5dgz) | Hard | Good one |
+|42| [415. Add Strings](https://tinyurl.com/y7cbq62x) | [Python](https://tinyurl.com/wu6rdaw/415_Add_Strings.py), [Swift](https://tinyurl.com/wuja3c4/415_Add_Strings.swift) | [Art 1](https://tinyurl.com/y6v9uj9o) | Easy | --- |
 
 
 </p>

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/415_Add_Strings.swift

@@ -0,0 +1,27 @@
+import Foundation
+class Solution {
+    func addStrings(_ num1: String, _ num2: String) -> String {
+        var digits1: [Int] = num1.compactMap { $0.wholeNumberValue }
+        var digits2: [Int] = num2.compactMap { $0.wholeNumberValue }
+        var carry = 0
+        var resultStack: [Int] = []
+        while digits1.count > 0 || digits2.count > 0 {
+            var (digit1, digit2) = (0, 0)
+            if digits1.count > 0 {
+                digit1 = digits1.popLast()!
+            }
+            if digits2.count > 0 {
+                digit2 = digits2.popLast()!
+            }
+            let sum = digit1 + digit2 + carry
+            let remainder = sum % 10
+            carry = sum / 10
+            resultStack.append(remainder)
+        }
+        if carry > 0 {
+            resultStack.append(carry)
+        }
+        resultStack = resultStack.reversed()
+        return resultStack.reduce("", { $0 + String($1)})
+    }
+}