# LeetCode 374. Guess Number Higher or Lower in F#

## URL

leetcode.com/problems/guess-number-higher-o..

## Code

github.com/syohex/dotnet-study/blob/master/..

```
let mutable picked = 0
let guess (n: int) : int =
if n > picked then -1
elif n = picked then 0
else 1
let guessNumber (n: int) : int =
let rec guessNumber' left right =
let mid = left + ((right - left) / 2)
match guess mid with
| 0 -> mid
| -1 -> guessNumber' left (mid - 1)
| 1 -> guessNumber' (mid + 1) right
| _ -> failwith "never reach here"
guessNumber' 1 n
```