SDE - 1

You are given an array of integers ‘coins’ denoting the denomination of coins and another array of integers ‘freq’ denoting the number of coins of each denomination.

You have to find the number of ways to make the sum ‘V’ by selecting some(or all) coins from the array.

The answer can be very large. So, return the answer modulo 1000000007.

For Example :

‘N’ = 3, ‘coins’ = {1, 2, 3}, ‘freq’ = {1, 1, 3}, ‘V’ = 6

For the given example, we can make six by using the following coins:
{1, 2, 3}
{3. 3}
Hence, the answer is 2.

maxProfit = 0
if price[i] > price[i – 1]
maxProfit = maxProfit + price[i] – price[i – 1]

You have been given a long type array/list 'arr’ of size 'n’.

It represents an elevation map wherein 'arr[i]’ denotes the elevation of the 'ith' bar.

Print the total amount of rainwater that can be trapped in these elevations.

Note :

The width of each bar is the same and is equal to 1.

Example:

Input: ‘n’ = 6, ‘arr’ = [3, 0, 0, 2, 0, 4].

Output: 10

Explanation: Refer to the image for better comprehension:

Note :

You don't need to print anything. It has already been taken care of. Just implement the given function.

You are given a Binary Search Tree (BST) and a target value ‘K’. Your task is to return true if there exist two nodes in the given BST such that the sum of their values is equal to the given target ‘K’, else return false.

A binary search tree (BST) is a binary tree data structure which has the following properties.

• The left subtree of a node contains only nodes with data less than the node’s data.

• The right subtree of a node contains only nodes with data greater than the node’s data.

• Both the left and right subtrees must also be binary search trees.

Note:

1. All the elements of the Binary Search Tree are unique.

2. You can’t use the same node value/element of BST twice.

For example:

tree: 8 5 10 2 6 -1 -1 -1 -1 -1 7 -1 -1
'K' = 13,

The nodes with values 8 and 5 as shown in the above figure gives sum equal to the given target 13. 

Therefore, the output will be “true” i.e it is possible to find a pair in the given BST having sum equal to ‘K’.

There are ‘N’ people at a party. Each person has been assigned a unique id between 0 to 'N' - 1(both inclusive). A celebrity is a person who is known to everyone but does not know anyone at the party.

Given a helper function ‘knows(A, B)’, It will returns "true" if the person having id ‘A’ know the person having id ‘B’ in the party, "false" otherwise. Your task is to find out the celebrity at the party. Print the id of the celebrity, if there is no celebrity at the party then print -1.

Note:

1. The helper function ‘knows’ is already implemented for you.
2. ‘knows(A, B)’ returns "false", if A doesn't know B.
3. You should not implement helper function ‘knows’, or speculate about its implementation.
4. You should minimize the number of calls to function ‘knows(A, B)’.
5. There are at least 2 people at the party.
6. At most one celebrity will exist.

Design an Api which implement 3 function:
1: Search in a list(Employees) on the basis of params
2: Add in a list
3: Remove from a list(with Employee ID)