F#真优美...

QuickSort

 

let rec quickSort = function
    | [] -> []
    | pivot::rest ->
        let left, right = List.partition (fun x -> x < pivot) rest
        quickSort left @ [pivot] @ quickSort right

 

测试代码

 

open System;
let mutable random = new Random();
[1..100]
|> List.map (fun x -> random.Next(1000))
|> quickSort
|> printfn "%A"

 

Huffman Tree

 

//Data Structure Definition
type tree = 
    | Node of string * float * tree * tree
    | Null
let ArrayToTrees arr = 
    [ for x in arr ->
        let (c, f) = x
        Node(c, f, Null, Null)]

//get data
open System;
open System.IO;
let lines = File.ReadAllLines(@"C:\Users\v-grw\Desktop\Data.txt")
let mutable trees = 
    lines 
    |> Array.map (fun x -> 
        let strParts = x.Split(',')
        (strParts.[0], Double.Parse(strParts.[1])))
    |> Seq.ofArray
    |> ArrayToTrees

//Huffman tree
for i in [1..trees.Length - 1] do
    trees <- trees |> List.sortBy (fun x ->
        match x with
        | Node(s, f, l, r) -> f
        | Null -> Double.MaxValue)
    match trees.[0] with
    | Node(s1, f1, l1, r1) ->
        match trees.[1] with
        | Node(s2, f2, l2, r2) ->
            let newTree = Node(s1 + s2, f1 + f2, trees.[0], trees.[1]);
            trees <- 
                [2..trees.Length - 1]
                |> List.map (fun i -> trees.[i])
                |> List.append [newTree]

printfn "%A" trees.[0]

 

不论是对树的定义还是建树的过程都很美...