SDE - 1

You are given ‘N’ items. Each item either doesn’t belong to any group or belongs to exactly one group out of ‘M’ groups. For each item, you are also given a list, ‘BEFORE’, containing items that should appear before this item in the final sorted list.

Your task is to sort these items in an order which follows the following rules :

The items belonging to the same group must be ordered adjacent to each other.
The item which does not belong to any group can be placed anywhere. 
Each item appearing in BEFORE[i] must be placed before the ith item in the sorted list.

Ninja is assigned a task to deliver some boxes which contain different units having different weights. With the help of his truck, he will earn money on the basis of the number of units of boxes he will deliver by his truck. Ninja truck has some capacity on the number of boxes he can put on his truck.

So your task is to find a way so that ninja will choose boxes in a way that units will be maximum and he would be able to get more money you will be provided with an array of ‘BOX’, where BOX[i] = [countofBoxes, unitsperBox].

CountofBoxes represents the number of boxes of the same type i.e containing the units of the same value.

UnitsperBox represents the number of units in the box or we simply say that unit value.

And an integer ‘K’ denoting the limit of boxes on the truck.

You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to return the list of all pairs of elements such that each sum of elements of each pair equals 'S'.

Note:

Each pair should be sorted i.e the first value should be less than or equals to the second value. 

Return the list of pairs sorted in non-decreasing order of their first value. In case if two pairs have the same first value, the pair with a smaller second value should come first.

A doubly-linked list is a data structure that consists of sequentially linked nodes, and the nodes have reference to both the previous and the next nodes in the sequence of nodes.

You are given a sorted doubly linked list of size 'n'.

Remove all the duplicate nodes present in the linked list.

Example :

Input: Linked List: 1 <-> 2 <-> 2 <-> 2 <-> 3

Output: Modified Linked List: 1 <-> 2 <-> 3

Explanation: We will delete the duplicate values ‘2’ present in the linked list.

You are given an integer grid of size ‘N’x’M’, and the cell of the grid contains either of the three values:

0 - An empty cell.

1 - A fresh orange.

2 - A rotten orange.

Every minute, any fresh orange adjacent(4-directionally) to a rotten orange becomes rotten.

You must return the minimum time after which no fresh oranges are left. Return -1 if it's impossible to rot all the fresh oranges.

Example:

Input: [[2,1,1],[1,1,0],[0,0,0]]

Output: 2

At T=0, only orange at (0,0) is rotten.
At T=1, oranges at (0,0),(0,1) and (1,0) are rotten.
At T=2, oranges at (0,0),(0,1),(1,0),(0,2) and (1,1) are rotten. 
No fresh oranges are left after T=2.

You are given two non-negative numbers 'num1' and 'num2' represented in the form of linked lists.

The digits in the linked lists are stored in reverse order, i.e. starting from least significant digit (LSD) to the most significant digit (MSD), and each of their nodes contains a single digit.

Calculate the sum of the two numbers and return the head of the sum list.

Example :

Input:
'num1' : 1 -> 2 -> 3 -> NULL
'num2' : 4 -> 5 -> 6 -> NULL

Output: 5 -> 7 -> 9 -> NULL

Explanation: 'num1' represents the number 321 and 'num2' represents 654. Their sum is 975.

Given a ‘N’ * ’M’ maze with obstacles, count and return the number of unique paths to reach the right-bottom cell from the top-left cell. A cell in the given maze has a value '-1' if it is a blockage or dead-end, else 0. From a given cell, we are allowed to move to cells (i+1, j) and (i, j+1) only. Since the answer can be large, print it modulo 10^9 + 7.

For Example :

Consider the maze below :
0 0 0 
0 -1 0 
0 0 0

There are two ways to reach the bottom left corner - 

(1, 1) -> (1, 2) -> (1, 3) -> (2, 3) -> (3, 3)
(1, 1) -> (2, 1) -> (3, 1) -> (3, 2) -> (3, 3)

Hence the answer for the above test case is 2.