G面经： Design Stock Price Display System

Implement a simple stock price display systemwhich will show High, Low and Last price for a given stock throughout one day.The data comes from a real-time feed and have the following messages:
PriceUpdate(t, P) -> Price of Stock A at timet is P.
Correction(t, NewP) -> Price of Stock A attime t is rectified to NewP
Remove(t) -> Disregard the price feedreceived at time t.
PriceUpdate(10100,850.50) -> high = 850.50, Low = 850.50, Last = 850.50
PriceUpdate(10200,852.25) -> high = 852.25, Low = 850.50, Last = 852.25
PriceUpdate(10300,848.00) -> high = 852.25, Low = 848.00, Last = 848.00
Correction(10200, 849.00) -> high = 850.50, Low = 848.00, Last 848.00
PriceUpdate(10400,855.00)  -> high = 855.00, Low = 848.00, Last = 855.00
Correction(10300, 853.00) -> high = 855.00, Low = 850.50, Last = 855.00
PriceUpdate(10500,854.00) -> high = 855.00, Low = 848.00, Last = 854.00
Correction(10500,853.25) -> high = 855.00, Low = 848.00, Last = 853.25
Remove(10300) -> high = 855.00, Low = 849.00, Last = 853.25

简单说来PriceUpdate就是添加新的（timestamp, price）, Correction是改之前的(timestamp, price), 求实现当前high(), low(), last()

简单说来PriceUpdate就是添加新的（timestamp, price）, Correction是改之前的(timestamp, price), 求实现当前high(), low(), last()

LZ是用的Heap + HashMap, 特别问了时间复杂度(我猜到他想考heap的remove(obj)复杂度)

follow Up是: 有没有办法把复杂度降到O(logN)

 

LZ是用的Heap + HashMap, 特别问了时间复杂度(我猜到他想考heap的remove(obj)复杂度)

LZ是用treeMap代替了Heap，这样代价是每次找high,low也要logN search整个tree了

 

感觉需要2个数据结构：
1. TreeMap<Long, Double> time2priceMap. 
2. TreeMap<Double, Integer> price2countMap

priceupdate: insert new record into time2priceMap, update price count in price2countmap
correction: update record in time2pricemap, update prev price count, update prev price count (if 0, remove record), update new price count or needs to insert a new price record into price2countmap
high and low: lastkey and firstkey from price2countmap
last: last entry's price from time2pricemap

补充内容 (2017-2-4 07:00):
这样好像都是O(log(n))