SDE - 1

You are given 'N' rectangular buildings in a 2-dimensional city. Your task is to compute the skyline of these buildings, eliminating hidden lines return the skyline formed by these buildings collectively. A city's skyline is the outer contour of the silhouette formed by all the buildings in that city when viewed from a distance. The geometric information of each building is given in the array of buildings where BUILDINGS[i] = [LEFT_i, RIGHT_i, HEIGHT_i]:

-> LEFT_i is the x coordinate of the left edge of the ith building.

-> RIGHT_i is the x coordinate of the right edge of the ith building.

-> HEIGHT_i is the height of the ith building.

You may assume all buildings are perfect rectangles grounded on an absolutely flat surface at height 0.

The skyline should be represented as a list of "key points" sorted by their x-coordinate in the form [[x1, y1], [x2, y2], ...]. Each key point is the left endpoint of some horizontal segment in the skyline except the last point in the list, which always has a y-coordinate 0 and is used to mark the skyline's termination where the rightmost building ends. Any ground between the leftmost and rightmost buildings should be part of the skyline's contour.

Note:

There must be no consecutive horizontal lines of equal height in the output skyline. For instance, [...,[2 3], [4 5], [7 5], [11 5], [12 7],...] is not acceptable; the three lines of height 5 should be merged into one in the final output.

As such: [..., [2 3], [4 5], [12 7],...]. 

Also, the buildings are sorted by a non-decreasing order.

For more clarification see sample case 1.

You have been given a sorted (lexical order) dictionary of an alien language.

Write a function that returns the order of characters as a string in the alien language. This dictionary will be given to you as an array of strings called 'dictionary', of size 'N'.

Example :

If the dictionary consists of the following words:-
["caa", "aaa", "aab"], and 'K' is 3.

Then, the order of the alphabet is -
['c', 'a', 'b']

Note:

If the language consists of four letters, the four letters should be the starting four letters of the English language. 

However, their order might differ in the alien language.

Ninja has found his new passion for photography. He has clicked some really good photos but in one of his images, he doesn’t like the color of a particular region. So, he decides to change the color of that region. Can you help him with this task?

The image is represented in the form of a 2D array of size M * N. Each pixel in the image is a positive integer. Ninja has given you the coordinates (row and column) of a certain pixel and the new color value. You need to replace the color of the given pixel and all adjacent same-colored pixels with the new color.

Note:

Two pixels are adjacent if they are connected to each other in any of the four directions: up, down, left, or right.

Diagonal pixels are not considered adjacent.

Example:

Consider the image of size 4*4, shown below (left). Let the coordinates of the starting pixel are (1, 2) and the new color is 8. The starting pixel, highlighted with red color, has a pixel value of 3. 

On replacing the given pixel and all adjacent same-colored pixels with the new color we get the new image, shown below (right). The modified pixels are highlighted with green color.

You are given a string 'str' of length 'N'.

Your task is to reverse the original string word by word.

There can be multiple spaces between two words and there can be leading or trailing spaces but in the output reversed string you need to put a single space between two words, and your reversed string should not contain leading or trailing spaces.

Example :

If the given input string is "Welcome to Coding Ninjas", then you should return "Ninjas Coding to Welcome" as the reversed string has only a single space between two words and there is no leading or trailing space.