Erlang 选择最高出价答案

【问题标题】：Erlang Select highest bidsErlang 选择最高出价
【发布时间】：2020-01-19 12:57:33
【问题描述】：

在下面的 select_highest_bids 函数中，使用 orddict:new() 代替 list 是否更好，如下所示？

OrderedBatches = lists:foldl(fun high_bid_filter/2, orddict:new(), Campaigns)

我们如何更改 high_bid_filter 以返回 orddict ？

select_highest_bids(Campaigns, BidRequest) ->
    lists:map(fun({_, C}) -> C end,
    lists:foldl(fun high_bid_filter/2, [], Campaigns),


high_bid_filter(Campaign = #campaign_response{bid = BR = #bid_response{ad_id = AdID, cpm_bid = Score}}, Campaigns) ->

    case lists:keyfind(AdID, 1, Campaigns) of
        false ->
            [{AdID, Campaign}|Campaigns];
        {AdID, _ = #campaign_response{bid = _ = #bid_response{cpm_bid = EB}}} when EB >= Score ->
            Campaigns;
        {AdID, _ = #campaign_response{bid = _ = #bid_response{cpm_bid = EB}}} when EB < Score ->
            lists:keystore(AdID, 1, Campaigns, {AdID, Campaign})
    end.

【问题讨论】：

标签： list dictionary erlang

【解决方案1】：

这里是文件夹功能

high_bid_filter(Campaign = #campaign_response{bid = #bid_response{ad_id = AdID, cpm_bid = Score}}, Campaigns) ->
  case orddict:take(AdID, Campaigns) of
    {V, _} when V >= Score -> 
      % find value but higher than Offer
      Campaigns;
    {V, Dict} ->
      % update higher value
      orddict:store(AdID, Campaign, Dict);
    error -> 
      % 
      orddict:store(AdID, Campaign, Campaigns)
  end.

希望对你有帮助

【讨论】：