SDE - 1

You are given an array/list 'prices' where the elements of the array represent the prices of the stock as they were yesterday and indices of the array represent minutes. Your task is to find and return the maximum profit you can make by buying and selling the stock. You can buy and sell the stock only once.

Note:

You can’t sell without buying first.

For Example:

For the given array [ 2, 100, 150, 120],
The maximum profit can be achieved by buying the stock at minute 0 when its price is Rs. 2 and selling it at minute 2 when its price is Rs. 150.
So, the output will be 148.

Ninja developed a love for arrays and strings so this time his teacher gave him an array of strings, ‘A’ of size ‘N’. Each element of this array is a string. The teacher taught Ninja about prefixes in the past, so he wants to test his knowledge.

A string is called a complete string if every prefix of this string is also present in the array ‘A’. Ninja is challenged to find the longest complete string in the array ‘A’.If there are multiple strings with the same length, return the lexicographically smallest one and if no string exists, return "None".

Note :

String ‘P’ is lexicographically smaller than string ‘Q’, if : 

1. There exists some index ‘i’ such that for all ‘j’ < ‘i’ , ‘P[j] = Q[j]’ and ‘P[i] < Q[i]’. E.g. “ninja” < “noder”.

2. If ‘P’ is a prefix of string ‘Q’, e.g. “code” < “coder”.

Example :

N = 4
A = [ “ab” , “abc” , “a” , “bp” ] 

Explanation : 

Only prefix of the string “a” is “a” which is present in array ‘A’. So, it is one of the possible strings.

Prefixes of the string “ab” are “a” and “ab” both of which are present in array ‘A’. So, it is one of the possible strings.

Prefixes of the string “bp” are “b” and “bp”. “b” is not present in array ‘A’. So, it cannot be a valid string.

Prefixes of the string “abc” are “a”,“ab” and “abc” all of which are present in array ‘A’. So, it is one of the possible strings.

We need to find the maximum length string, so “abc” is the required string.

You are given a tree with ‘N’ nodes and ‘N-1’ edges. Your task is to determine the tree's maximum height when we consider any arbitrary node as a root.

For Example:

N = 4
Edges = [2 3], [4 3], [1 3]

Output: 2

Here node 4 is at a distance 2 from node 1 and if we make node 1 as a root, it will give the height of 2, which is the maximum possible in this tree.

You are given an array/list ARR consisting of N integers. Your task is to find the maximum possible sum of a non-empty subarray(contagious) of this array.

Note: An array C is a subarray of array D if it can be obtained by deletion of several elements(possibly zero) from the beginning and the end of array D.

For e.g.- All the non-empty subarrays of array [1,2,3] are [1], [2], [3], [1,2], [2,3], [1,2,3].

Questions about Inheritance, Polymorphism, etc. And to explain using some examples.

I was asked to write multiple sql queries for an example db. Like getting all records with some conditions, self join, left join, etc.