SDE - 2

You have been given two arrays, 'AT' and 'DT', representing the arrival and departure times of all trains that reach a railway station.

Your task is to find the minimum number of platforms required for the railway station so that no train needs to wait.

Note :

1. Every train will depart on the same day and the departure time will always be greater than the arrival time. For example, A train with arrival time 2240 and departure time 1930 is not possible.

2. Time will be given in 24H format and colons will be omitted for convenience. For example, 9:05AM will be given as "905", or 9:10PM will be given as "2110".

3. Also, there will be no leading zeroes in the given times. For example, 12:10AM will be given as “10” and not as “0010”.

You are given a string 'str' of lowercase alphabets and an integer 'k' .

Your task is to return the count all the possible substrings that have exactly 'k' distinct characters.

For example:

'str' = abcad and 'k' = 2. 

We can see that the substrings {ab, bc, ca, ad} are the only substrings with 2 distinct characters. 

Therefore, the answer will be 4.    

You are given an array arr of length N. You have to return a list of integers containing the NGE(next greater element) of each element of the given array. The NGE for an element X is the first greater element on the right side of X in the array. Elements for which no greater element exists, consider the NGE as -1.

For Example :

If the given array is [1, 3, 2], then you need to return [3, -1, -1]. Because for 1, 3 is the next greater element, for 3 it does not have any greater number to its right, and similarly for 2.

You have been given the preorder and inorder traversal of a binary tree. Your task is to construct a binary tree using the given inorder and preorder traversals.

Note:

You may assume that duplicates do not exist in the given traversals.

For example :

For the preorder sequence = [1, 2, 4, 7, 3] and the inorder sequence = [4, 2, 7, 1, 3], we get the following binary tree.

Ishita has 10 bags full of coins. Each bag contains 1000 coins. But one bag is full of forgeries, and she just can’t recall which one. She does know that genuine coins weigh 1 gram, but forgeries weigh 1.1 grams. To hide the fact that she can’t recall which bag contains forgeries, she needs your help. How can she identify the bag with the forgeries with just one weighing?