SDE - 1

You are given an array of integers 'ARR' containing N elements. Each integer is in the range [1, N-1], with exactly one element repeated in the array.

Your task is to find the duplicate element. The duplicate element may be repeated more than twice in the error, but there will be exactly one element that is repeated in the array.

Note :

All the integers in the array appear only once except for precisely one integer which appears two or more times.

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 are given a Binary Tree.

Return the length of the diameter of the tree.

Note :

The diameter of a binary tree is the length of the longest path between any two end nodes in a tree.

The number of edges between two nodes represents the length of the path between them.

Example :

Input: Consider the given binary tree:

Output: 6

Explanation:
Nodes in the diameter are highlighted. The length of the diameter, i.e., the path length, is 6.

You have been given an array/list 'ARR' of integers. Your task is to find the second largest element present in the 'ARR'.

Note:

a) Duplicate elements may be present.

b) If no such element is present return -1.

Example:

Input: Given a sequence of five numbers 2, 4, 5, 6, 8.

Output:  6

Explanation:
In the given sequence of numbers, number 8 is the largest element, followed by number 6 which is the second-largest element. Hence we return number 6 which is the second-largest element in the sequence.

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