Code Golf: Lights out

Answer 1

F#, 365 370, 374, 444 including all whitespace

open System
let s(r:string)=
    let d=r.IndexOf"\n"
    let e,m,p=d+1,r.ToCharArray(),Random()
    let o b k=m.[k]<-char(b^^^int m.[k])
    while String(m).IndexOfAny([|'*';'\\'|])>=0 do
        let x,y=p.Next d,p.Next d
        o 118(x+y*e)
        for i in x-1..x+1 do for n in y-1..y+1 do if i>=0&&i=0&&n

Here's the original readable version before the xor optimization. 1108

open System

let solve (input : string) =
    let height = input.IndexOf("\n")
    let width = height + 1

    let board = input.ToCharArray()
    let rnd = Random()

    let mark = function
        | '*' -> 'O'
        | '.' -> 'X'
        | 'O' -> '*'
        |  _  -> '.'

    let flip x y =
        let flip = function
            | '*' -> '.'
            | '.' -> '*'
            | 'X' -> 'O'
            |  _  -> 'X'

        if x >= 0 && x < height && y >= 0 && y < height then
            board.[x + y * width] <- flip board.[x + y * width]

    let solved() =
        String(board).IndexOfAny([|'*';'O'|]) < 0

    while not (solved()) do
        let x = rnd.Next(height) // ignore newline
        let y = rnd.Next(height)

        board.[x + y * width] <- mark board.[x + y * width]

        for i in -1..1 do
            for n in -1..1 do
                flip (x + i) (y + n)

    printf "%s" (String(board))