SDE - 1

The Ultimate Ninja Ankush, after training hard, goes for a good meal at the ninja cafe, for that he follows the path given on the map, which may or may not lead him to the ninja cafe. The map is a directed graph. Since he is also very lazy, he wants to minimize the effort to travel. The effort is defined as the product of all the distance it takes to reach from the dojo (source) to the ninja cafe (destination). Can you help him find the path with the minimum effort it would take The Ultimate Ninja Ankush to reach the destination?

More Formally, you are given a directed graph with ‘N’ nodes and ‘M’ edges where the distance of each edge is greater than 0, also given a source ‘src’ and a destination ‘dest’. The task is to find the minimum product of edges from src’ to ‘dest’. If there is no path from ‘src’ to ‘dest’, then return -1.

For example

Given:
‘N’ = 3, ‘M’ = 3. 
‘edges’ = 
    [[0 1 1],
     [1 2 1],
     [0 2 3]]
‘src’ = 0, ‘dest’ = 2.

There are two possible paths, that is to go from node-0 to node-2 directly, which will take 2 units of effort, or go from node-0 to node-1 and then node-1 to node-2, which will take 1 unit of effort.

You have been given two arrays, 'AT' and 'DT', representing the arrival and departure times of all trains that reach a railway station.

Your task is to find the minimum number of platforms required for the railway station so that no train needs to wait.

Note :

1. Every train will depart on the same day and the departure time will always be greater than the arrival time. For example, A train with arrival time 2240 and departure time 1930 is not possible.

2. Time will be given in 24H format and colons will be omitted for convenience. For example, 9:05AM will be given as "905", or 9:10PM will be given as "2110".

3. Also, there will be no leading zeroes in the given times. For example, 12:10AM will be given as “10” and not as “0010”.

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.

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Follow up questions - 
What is critical section problem?
multithreading program.

Ninjas are often known for their stealth execution and accuracy to get the job done right. While honing their art of moving through dense forests stealthily, they need the maximum number of continuous trees one after the other for practicing.

Trees are represented by 1s and empty places by 0s (basically a binary representation of a given integer). You are also given an extra tree which you can plant at any empty place (i.e. you can flip one of the zeroes in the binary representation to 1). The tree should be planted such that the maximum number of consecutive trees is maximized.

Your task is to report the maximum number of consecutive trees after plantation.

Note:

You may also choose not to plant that extra tree at all.

For Example:

Input: 54
Output: 5

The binary representation of 54 is 110110.
After flipping the third bit from the left, we get consecutive 5 bits. i.e. 111110.

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