URL
Add Binary - LeetCode
Code
https://github.com/syohex/dotnet-study/tree/master/fsharp/leetcode/challenge/202302/add_binary/main.fsx
open System
let addBinary (a: string) (b: string) : string =
let rec addBinary' ca cb carry (acc: char list) =
match ca, cb with
| [], [] ->
if carry = 1 then
String.Concat('1' :: acc)
else
String.Concat acc
| h :: t, [] ->
match h + carry with
| 2 -> addBinary' t [] 1 ('0' :: acc)
| 1 -> addBinary' t [] 0 ('1' :: acc)
| 0 -> addBinary' t [] 0 ('0' :: acc)
| _ -> failwith "never reach here"
| [], h :: t ->
match h + carry with
| 2 -> addBinary' [] t 1 ('0' :: acc)
| 1 -> addBinary' [] t 0 ('1' :: acc)
| 0 -> addBinary' [] t 0 ('0' :: acc)
| _ -> failwith "never reach here"
| h1 :: t1, h2 :: t2 ->
match h1 + h2 + carry with
| 3 -> addBinary' t1 t2 1 ('1' :: acc)
| 2 -> addBinary' t1 t2 1 ('0' :: acc)
| 1 -> addBinary' t1 t2 0 ('1' :: acc)
| 0 -> addBinary' t1 t2 0 ('0' :: acc)
| _ -> failwith "never reach here"
let strToIntList = Seq.map (fun c -> int c - int '0') >> Seq.rev >> Seq.toList
let ca, cb = strToIntList a, strToIntList b
addBinary' ca cb 0 []
