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)}.

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.

You are given a non-empty binary tree where each node has a non-negative integer value. Return the maximum possible sum of path between any two leaves of the given tree.

The path is also inclusive of the leaf nodes and the maximum path sum may or may not go through the root of the given tree.

If there is only one leaf node in the tree, then return -1.

You have been given a network of ‘N’ nodes from 1 to ‘N’ and ‘M’ edges. For each edge, you are given three values (ui, vi, wi) where “ui” and “vi” denote the nodes and “wi” denotes an integer value which represents the time taken by a signal to travel from “ui” to “vi”. Now, you are supposed to find the time which a signal takes to travel from a given node ‘K’ to all nodes. If it is impossible for all nodes to receive the signal then print -1.

Note:

The signal which starts from the source node travels to all nodes simultaneously.