head(tail(head(tail(H))))
(b)
(xyz)
(de)
GetHead(GetHead(GetTail(L)))
本算法中首先數組b中元素以逆置順序放入d數組中然後數組a和數組d的元素比較將大者拷貝到數組c第一個WHILE循環到數組a或數組d結尾第二個和第三個WHILE語句只能執行其中的一個
（）b[mi+]（）x:=a[i]（）i:=i+（）x:=d[j]（）j:=j+ （）k:=k+（）i<=l（）j<=m
（）(i==k) return（）i+（）i（）i!=k
本算法利用快速排序思想找到第k個元素的位置（下標k因而開初有k）內層do循環以t(t=a[low])為樞軸找到其應在i位置這時若i等於k則算法結束（即第一個空格處if(i==k) return)否則若i<k就在i+至high中間去查若i>k則在low到i間去找直到找到i=k為止
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From:http://tw.wingwit.com/Article/program/sjjg/201311/23064.html
