SDE - Intern

You are given a ‘root’ of the binary tree, and you have to return the sum of all nodes present at the Kth level from the top. The root node is considered as level 1, and below it is level 2, and so on.

Note:

A binary tree is a tree in which each node has at most 2 children.

Example:

For Example, the root node is given as follows :
‘ROOT’ = 1 2 3 4 -1 -1 5 -1 -1 -1 -1 and ‘K’ = 2, Then the sum of all nodes at K-level will be 5. This is because 2 and 3 are present at level 2 and 2 + 3 = 5. Therefore 5 is the answer.

Given an undirected graph, find how many triangles it can have where a triangle is a cyclic path of length three which begins and end at the same vertex.

#### An undirected graph is a graph in which if you can go from a vertex, say, ‘A’ to ‘B,’ you can come back to ‘A’ from ‘B.’

For example:

In this graph, we can visit from vertex 1 to 2, then we can also visit from vertex 2 to 1. This is true for all vertices.

Given an array of numbers, find the maximum sum of any contiguous subarray of the array.

For example, given the array [34, -50, 42, 14, -5, 86], the maximum sum would be 137, since we would take elements 42, 14, -5, and 86.

Given the array [-5, -1, -8, -9], the maximum sum would be -1.

Follow up: Do this in O(N) time.