题意：给出一个序列，从序列中选k个元素，使序列最大值与最小值的差最小。

解法：排序后再对所有合理的i，比较a[i] 与 a[i+k]的差值，求其最小即可，时间花在排序上是，为O(NlogN)

import Data.List
main = do
    line<-getLine
    line<-getLine
    let g = (read line::Int) -1
    ctx <- getContents
    let p = sort [read x::Int| x<-lines ctx]
    print $ minVal (map dist (zip p (jump p g)))
jump :: [Int] -> Int ->[Int]
jump xs 0 = xs
jump xs s = jump (tail xs) (s-1)
dist :: (Int,Int)->Int
dist (x,y) = y-x
minVal :: [Int] -> Int
minVal (x:[]) =x
minVal (x:xs) = min x (minVal xs)