Erlang的堆排序
至于堆排内容和原理可以看一下博客
http://blog.youkuaiyun.com/feixiaoxing/article/details/6846664
http://www.cnblogs.com/dolphin0520/archive/2011/10/06/2199741.html
-module(heap_sort).
-compile(export_all).
%% 堆调整
heap_adjust(List, Start, End) when Start > End/2 -> List;
heap_adjust(List, Start, End) ->
heap_adjust_helper(List, Start, End).
heap_adjust_helper(List, Start, End) ->
Left = Start * 2,
Right = Start * 2 + 1,
%% 找出节点Left, Max, Start中对应值为最小的节点
Max = Start,
MaxAfLeft = get_max_index(Left, Max, End, List),
MaxAfRight = get_max_index(Right, MaxAfLeft, End, List),
case MaxAfRight /= Max of
true ->
NewList = swap(List, Start, MaxAfRight),
heap_adjust(NewList, MaxAfRight, End);
false ->
List
end.
%% 获得最大值的节点
get_max_index(T1, T2, End, _List) when T1 > End -> T2;
get_max_index(T1, T2, _End, List) ->
case lists:nth(T1, List) > lists:nth(T2, List) of
true -> T1;
false -> T2
end.
%% 初始化堆
build_heap(List) ->
Len = length(List),
I = trunc(Len / 2),
build_heap_helper(List, I, Len).
build_heap_helper(List, 0, _Len) -> List;
build_heap_helper(List, I, Len) ->
NewList = heap_adjust(List, I, Len),
build_heap_helper(NewList, I-1, Len).
%% 堆排
heap_sort(List) ->
Len = length(List),
NewList = build_heap(List),
heap_sort_helper(NewList, Len).
heap_sort_helper(List, 0) -> List;
heap_sort_helper(List, Len) ->
% io:format("~n M:~p L:~p List:~p ~n", [?MODULE, ?LINE, List]),
NewList1 = swap(List, 1, Len),
NewList2 = heap_adjust(NewList1, 1, Len - 1),
heap_sort_helper(NewList2, Len - 1).
%% 替换
swap(List, I, J) ->
VI = lists:nth(I, List),
VJ = lists:nth(J, List),
Tuple = list_to_tuple(List),
NewTuple1 = setelement(I, Tuple, VJ),
NewTuple2 = setelement(J, NewTuple1, VI),
NewList = tuple_to_list(NewTuple2),
NewList.
%% 测试代码
test() ->
List = random_number(20, 1000, 10, []),
heap_sort(List).
random_number( 0, _, _, L) -> L;
random_number(Size, Max, Min, L) ->
Num = random:uniform(Max-Min) + Min,
random_number(Size-1, Max, Min, [Num|L]).
%% 时间复杂度:O(nlogn)
%% 空间复杂度:O(1)