-module(exam).-compile(export_all).%1杨辉三角start(N) when is_integer(N) ->        print(N,1,1).%C表示行数%LC表示C对应的listprint(N,1,_) ->        io:format("~p~n",[[1]]),        print(N,2,1);print(N,2,_) ->        io:format("~p~n",[[1,1]]),        print(N,3,[1,1]);%Lc_minus_1 表示C-1行的listprint(N,C,Lc_minus_1) ->    if        C =:= (N + 1) ->            ok;        true    ->            LC = get_increment(C,Lc_minus_1,[1]),            io:format("~p~n",[LC]),            print(N,C+1,LC)    end.%L 是 N-1行 的列表%Result结果是 N行 的列表get_increment(N,L,Result) ->    Len = length(Result),     if        Len =:= N-1 -> [1|Result];        true ->            get_increment(N,L,[lists:nth(Len,L) + lists:nth(Len+1,L) | Result])    end.%2 选择排序select_sort(L) ->    select_sort_impl(L,[]).select_sort_impl([],_) ->    io:format("~n");select_sort_impl(L,Result) ->    {Pos,Value} = get_min(L),    L_new = lists:sublist(L,Pos-1) ++ lists:sublist(L,Pos+1,length(L)-Pos+1),    Result_new = Result ++ [Value],    io:format("~p~n",[Result_new ++ L_new]),    select_sort_impl(L_new,Result_new).get_min([]) ->    error;get_min(L) ->    %第一次取第一个元素为初始最小值    get_min_impl(L,1,1,lists:nth(1,L)).%获得list最小元素的{位置，值}%Idx 表示遍历到当前list的第几个get_min_impl([],_,Pos,Value) ->    {Pos,Value};get_min_impl(L,Idx,Pos,Value) ->    [H|T] = L,    if        H < Value ->            get_min_impl(T,Idx+1,Idx,H);        true      ->            get_min_impl(T,Idx+1,Pos,Value)    end.%3%交集insect(L1,L2) ->    lists:sort(insect_impl(lists:sort(L1),lists:sort(L2),[])).insect_impl(L1,L2,Result) ->    if        L1 =:= [];        L2 =:= [] ->            Result;        true ->            [H1|T1] = L1,            [H2|T2] = L2,            if                H1 =:= H2 ->                    insect_impl(T1,T2,[H1|Result]);                H1 <   H2 ->                    %pass H1                    insect_impl(T1,L2,Result);                true      ->                    %pass H2                    insect_impl(L1,T2,Result)            end    end.%并集union(L1,L2) ->    lists:sort(union_impl(lists:sort(L1),lists:sort(L2),[])).union_impl(L1,L2,Result) ->    if        L1 =:= [] ->            [L2|Result];        L2 =:= [] ->            [L1|Result];        true ->            [H1|T1] = L1,            [H2|T2] = L2,            if                H1 =:= H2 ->                    insect_impl(T1,T2,[H1|Result]);                true      ->                    insect_impl(T1,T2,[H1|[H2|Result]])            end    end.%4start(Alg, CacheSize) ->    case Alg of         lru ->            lru(CacheSize);        lfu ->            lfu(CacheSize)    end.lru(CacheSize) ->    {ok,S} = file:open("production-build00-2-4K.req",[read]),    lru_impl(S,CacheSize,[]),    file:close(S),    ok.    lru_impl(S,CacheSize,Cache) ->    R = file:read_line(S),    if        R == eof ->            ok;        true    ->            {ok,Line_} = R,            %删除\n            Line = string:sub_string(Line_,1,length(Line_)-1),            [_,_,Id] = string:tokens(Line," "),            case lists:member(Id,Cache) of                 true ->                    Cache_new = Cache;                false ->                    Len = length(Cache),                    if                        Len < CacheSize ->                            Cache_new = [Id|Cache];                        true            ->                            %lru                            Cache_new = [Id|lists:sublist(Cache,CacheSize-1)]                    end            end,            io:format("LRU Cache:~p~n",[Cache]),            lru_impl(S,CacheSize,Cache_new)   end.lfu(CacheSize) ->    {ok,S} = file:open("production-build00-2-4K.req",[read]),    lfu_impl(S,CacheSize,[]),    file:close(S),    ok.lfu_impl(S,CacheSize,Cache) ->    R = file:read_line(S),    if        R == eof ->            ok;        true    ->            {ok,Line_} = R,            %删除\n            Line = string:sub_string(Line_,1,length(Line_)-1),            [_,_,Id] = string:tokens(Line," "),            %tuple格式{id,count}            Tuple = lists:keyfind(Id,1,Cache),            if                %不存在Id                Tuple =:= false ->                    Len = length(Cache),                    if                        Len < CacheSize ->                            Cache_new = [{Id,1}|Cache];                        true            ->                            %lfu                            %按count升序排列                            [_|Cache_sorted_tail] = lists:keysort(2,Cache),                            Cache_new = [{Id,1}|Cache_sorted_tail]                    end;                %存在id，count+1                true ->                     {_,Count} = Tuple,                     Cache_new = lists:keystore(Id,1,Cache,{Id,Count+1})            end,            io:format("LFU Cache:~p~n",[Cache_new]),            lfu_impl(S,CacheSize,Cache_new)   end.