SDE - Intern

You are the manager of a hotel having 10 floors numbered 0-9. Each floor has 26 rooms [A-Z]. You will be given a sequence of strings of the room where ‘+’ suggests the room is booked and ‘-’ suggests the room is freed. You have to find which room is booked the maximum number of times.

Note:

You may assume that the sequence is always correct, i.e., every booked room was previously free, and every freed room was previously booked.

In case, 2 rooms have been booked the same number of times, you have to return Lexographically smaller room.

A string 'a' is lexicographically smaller than a string 'b' (of the same length) if in the first position where 'a' and 'b' differ, string 'a' has a letter that appears earlier in the alphabet than the corresponding letter in string 'b'. For example, "abcd" is lexicographically smaller than "acbd" because the first position they differ in is at the second letter, and 'b' comes before 'c'.

For Example :

n = 6, Arr[] = {"+1A", "+3E", "-1A", "+4F", "+1A", "-3E"}

Now in this example room “1A” was booked 2 times which is the maximum number of times any room was booked. Hence the answer is “1A”.

You are given a string that represents time in the format hh:mm. Some of the digits are blank (represented by ‘?’). Fill in ‘?’ such that the time represented by this string is the maximum possible. Maximum time: 23:59, minimum time: 00:00. You can assume that the input string is always valid.

For Example :

If the given input string is 1?:?8.
We can replace the first ‘?’ with 9 and second with 5 to get the maximum time of 19:58.

You have been given a number of stairs. Initially, you are at the 0th stair, and you need to reach the Nth stair.

Each time, you can climb either one step or two steps.

You are supposed to return the number of distinct ways you can climb from the 0th step to the Nth step.

Note:

Note: Since the number of ways can be very large, return the answer modulo 1000000007.

Example :

N=3

We can climb one step at a time i.e. {(0, 1) ,(1, 2),(2,3)} or we can climb the first two-step and then one step i.e. {(0,2),(1, 3)} or we can climb first one step and then two step i.e. {(0,1), (1,3)}.

Make a E-R Diagram for OLA serive .
You need to think of the Backend Process. 
Like what happens when you book, who is assigning you the drivers etc.