Sudoku: Difference between revisions

/// Dictionary of all peer squares in the relevant units wrt square in question

let peers =

|> Map.ofList

 

/// Eliminate d from values[s] and propagate when values = 1.

/// Return Some values, except return None if a contradiction is detected.

match Seq.length vx[s] with // (1) If a square s is reduced to one value d, then eliminate d from the peers.

| 0 -> None // removed last value

let unitsElim vx =

units[s] // (2) If a unit u is reduced to only one place for a value d, then put it there.

let dKeys = [for s in u do if st[s] |> Seq.contains d then s]

match Seq.length dKeys with

 

/// Convert grid to a Map of constraint popagated possible values, or return None if a contradiction is detected.

let values = [for s in squares do s, digits]|> Map.ofList

parsedGrid