System Engineer

The node structure of a binary tree is modified such that each node has the reference to its parent node.

You are given two nodes: ‘N1’ and ‘N2’, of the above binary tree. Your task is to return the lowest common ancestor (LCA) of the given nodes.

Note:

Let ‘TREE’ be a binary tree. The lowest common ancestor of two nodes, ‘N1’ and ‘N2’, is defined as the lowest node in ‘TREE’ with ‘N1’ and ‘N2’ as descendants (where we allow a node to be a descendant of itself).

You are given an array 'a' of size 'n'.

Print the Next Greater Element(NGE) for every element.

The Next Greater Element for an element 'x' is the first element on the right side of 'x' in the array, which is greater than 'x'.

If no greater elements exist to the right of 'x', consider the next greater element as -1.

For example:

Input: 'a' = [7, 12, 1, 20]

Output: NGE = [12, 20, 20, -1]

Explanation: For the given array,

- The next greater element for 7 is 12.

- The next greater element for 12 is 20. 

- The next greater element for 1 is 20. 

- There is no greater element for 20 on the right side. So we consider NGE as -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.

The city of Ninjaland is analogous to the unweighted graph. The city has ‘N’ houses numbered from 1 to ‘N’ respectively and are connected by M bidirectional roads. If a road is connecting two houses ‘X’ and ‘Y’ which means you can go from ‘X’ to ‘Y’ or ‘Y’ to ‘X’. It is guaranteed that you can reach any house from any other house via some combination of roads. Two houses are directly connected by at max one road.

A path between house ‘S’ to house ‘T’ is defined as a sequence of vertices from ‘S’ to ‘T’. Where starting house is ‘S’ and the ending house is ‘T’ and there is a road connecting two consecutive houses. Basically, the path looks like this: (S , h1 , h2 , h3 , ... T). you have to find the shortest path from ‘S’ to ‘T’.

For example

In the below map of Ninjaland let say you want to go from S=1 to T=8, the shortest path is (1, 3, 8). You can also go from S=1 to T=8  via (1, 2, 5, 8)  or (1, 4, 6, 7, 8) but these paths are not shortest.

You have been given an undirected graph of ‘V’ vertices (labeled 0,1,..., V-1) and ‘E’ edges. Each edge connecting two nodes (‘X’,’Y’) will have a weight denoting the distance between node ‘X’ and node ‘Y’.

Your task is to find the shortest path distance from the source node, which is the node labeled as 0, to all vertices given in the graph.

Example:

Input:
4 5
0 1 5
0 2 8
1 2 9
1 3 2
2 3 6

In the given input, the number of vertices is 4, and the number of edges is 5.

In the input, following the number of vertices and edges, three numbers are given. The first number denotes node ‘X’, the second number denotes node ‘Y’ and the third number denotes the distance between node ‘X’ and ‘Y’.

As per the input, there is an edge between node 0 and node 1 and the distance between them is 5.

The vertices 0 and 2 have an edge between them and the distance between them is 8.
The vertices 1 and 2 have an edge between them and the distance between them is 9.
The vertices 1 and 3 have an edge between them and the distance between them is 2.
The vertices 2 and 3 have an edge between them and the distance between them is 6.

Note:

1. There are no self-loops(an edge connecting the vertex to itself) in the given graph.

2. There can be parallel edges i.e. two vertices can be directly connected by more than 1 edge.

Given a string S containing digits from 2 to 9 inclusive. Your task is to find all possible letter combinations that the number could represent.

A mapping from Digits to Letters (just like in Nokia 1100) is shown below. Note that 1 does not map to any letter.