SDE - 1

You have been given a number of stairs. Initially, you are at the 0th stair, and you need to reach the Nth stair.

Each time, you can climb either one step or two steps.

You are supposed to return the number of distinct ways you can climb from the 0th step to the Nth step.

Note:

Note: Since the number of ways can be very large, return the answer modulo 1000000007.

Example :

N=3

We can climb one step at a time i.e. {(0, 1) ,(1, 2),(2,3)} or we can climb the first two-step and then one step i.e. {(0,2),(1, 3)} or we can climb first one step and then two step i.e. {(0,1), (1,3)}.

Design a data structure to implement deque of size ‘N’. It should support the following operations:

pushFront(X): Inserts an element X in the front of the deque. Returns true if the element is inserted, otherwise false.

pushRear(X): Inserts an element X in the back of the deque. Returns true if the element is inserted, otherwise false.

popFront(): Pops an element from the front of the deque. Returns -1 if the deque is empty, otherwise returns the popped element.

popRear(): Pops an element from the back of the deque. Returns -1 if the deque is empty, otherwise returns the popped element.

getFront(): Returns the first element of the deque. If the deque is empty, it returns -1.

getRear(): Returns the last element of the deque. If the deque is empty, it returns -1.

isEmpty(): Returns true if the deque is empty, otherwise false.

isFull(): Returns true if the deque is full, otherwise false.

Following types of queries denote these operations:

Type 1: for pushFront(X) operation.
Type 2: for pushRear(X) operation.
Type 3: for popFront() operation.
Type 4: for popRear() operation.
Type 5: for getFront() operation.
Type 6: for getRear() operation.
Type 7: for isEmpty() operation.
Type 8: for isFull() operation.

You have been given a gold mine represented by a 2-d matrix of size ('N' * 'M') 'N' rows and 'M' columns. Each field/cell in this mine contains a positive integer, the amount of gold in kgs.

Initially, the miner is at the first column but can be at any row.

He can move only right, right up, or right down. That is from a given cell and the miner can move to the cell diagonally up towards the right or right or diagonally down towards the right.

Find out the maximum amount of gold he can collect.

You are given a binary tree having 'n' nodes.

The boundary nodes of a binary tree include the nodes from the left and right boundaries and the leaf nodes, each node considered once.

Figure out the boundary nodes of this binary tree in an Anti-Clockwise direction starting from the root node.

Example :

Input: Consider the binary tree A as shown in the figure:

Output: [10, 5, 3, 7, 18, 25, 20]

Explanation: As shown in the figure

The nodes on the left boundary are [10, 5, 3]

The nodes on the right boundary are [10, 20, 25]

The leaf nodes are [3, 7, 18, 25].

Please note that nodes 3 and 25 appear in two places but are considered once.