How would you design a logging system for something like Google , you should be able to query for the number of times a URL was opened within two time frames.

i/p : start_time , end_time , URL1 

o/p : number of times URL1 was opened between start and end time.

Some specs : Database is not an optimal solution A URL might have been opened multiple times for given time stamp. A URL might have been opened a large number of times within two time stamps. start_time and end_time can be a month apart. time could be granular to a second.

Assume your daily prices of a stock are 3 7 4 10 11 8 5 4 8 . You can only buy 1 share or sell 1 share a day, but you can only sell if you own the stock. You can't hold more than 1 share. write an algo that finds the strategy that has the highest pay off. Don't generate the all possible strategies and compare.

We're playing a game. Cards numbered from 1-10 are placed in a hat. whatever card is drawn is the paid out amount. how much should i charge you to play this game? If you can redraw by placing the first card back into the hat, what is the new price?

You have N guards in a line each with a demand of coins.You can skip paying a guard only if his demand is lesser than what you have totally paid before reaching him.Find the least number of coins you spend to cross all guards