# LeetCode 990. Satisfiability of Equality Equations in F#

Shohei Yoshida
·Sep 26, 2022·

## URL

leetcode.com/problems/satisfiability-of-equ..

## Code

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

``````let equationsPossible (equations: string list) : bool =
let rec createGraph (equations: string list) (graph: Set<int> []) =
match equations with
| [] -> graph
| h :: t ->
if h.[1] = '=' then
let a = int h.[0] - int 'a'
let b = int h.[3] - int 'a'

createGraph t graph
else
createGraph t graph

let rec colorGraph node color (graph: Set<int> []) (colors: int []) =
if colors.[node] <> -1 then
colors
else
colors.[node] <- color

graph.[node]
|> Set.fold (fun acc next -> colorGraph next color graph acc) colors

let rec equationsPossible' (equations: string list) (colors: int []) =
match equations with
| [] -> true
| h :: t ->
if h.[1] = '!' then
let a = int h.[0] - int 'a'
let b = int h.[3] - int 'a'

if colors.[a] = colors.[b] then
false
else
equationsPossible' t colors
else
equationsPossible' t colors

let graph = createGraph equations (Array.init 26 (fun _ -> Set.empty))

let colors =
seq { 0..25 }
|> Seq.fold (fun acc i -> colorGraph i i graph acc) (Array.zeroCreate 26)

equationsPossible' equations colors
``````