XML2 - Find the Maximum Depth

You are given a valid XML document, and you have to print the maximum level of nesting in it. Take the depth of the root as .

Input Format

The first line contains , the number of lines in the XML document. 
The next  lines follow containing the XML document.

Output Format

Output a single line, the integer value of the maximum level of nesting in the XML document.

Sample Input

6
<feed xml:lang='en'>
    <title>HackerRank</title>
    <subtitle lang='en'>Programming challenges</subtitle>
    <link rel='alternate' type='text/html' href='http://hackerrank.com/'/>
    <updated>2013-12-25T12:00:00</updated>
</feed>

Sample Output

1

Explanation

Here, the root is a feed tag, which has depth of . 
The tags title, subtitle, link and updated all have a depth of . 

Thus, the maximum depth is .

import xml.etree.ElementTree as etree

maxdepth = 0
def depth(elem, level):
    global maxdepth
    # your code goes here
    if (level == maxdepth):
        maxdepth += 1
    for child in elem:
        depth(child, level + 1)

if __name__ == '__main__':
    n = int(input())
    xml = ""
    for i in range(n):
        xml =  xml + input() + "\n"
    tree = etree.ElementTree(etree.fromstring(xml))
    depth(tree.getroot(), -1)
    print(maxdepth)

XML 1 - Find the Score

ou are given a valid XML document, and you have to print its score. The score is calculated by the sum of the score of each element. For any element, the score is equal to the number of attributes it has.

Input Format

The first line contains , the number of lines in the XML document.
The next  lines follow containing the XML document.

Output Format

Output a single line, the integer score of the given XML document.

Sample Input

6
<feed xml:lang='en'>
    <title>HackerRank</title>
    <subtitle lang='en'>Programming challenges</subtitle>
    <link rel='alternate' type='text/html' href='http://hackerrank.com/'/>
    <updated>2013-12-25T12:00:00</updated>
</feed>

Sample Output

5

Explanation

The feed and subtitle tag have one attribute each - lang. 
The title and updated tags have no attributes. 
The link tag has three attributes - rel, type and href. 

So, the total score is . 

There may be any level of nesting in the XML document. To learn about XML parsing, refer here. 

NOTE: In order to parse and generate an XML element tree, use the following code:

>> import xml.etree.ElementTree as etree
>> tree = etree.ElementTree(etree.fromstring(xml))

Here, XML is the variable containing the string.
Also, to find the number of keys in a dictionary, use the len function:

>> dicti = {'0': 'This is zero', '1': 'This is one'}
>> print (len(dicti))

2

import sys
import xml.etree.ElementTree as etree

def get_attr_number(node):
    # your code goes here
    #return sum([len(elem.items()) for elem in node.iter()])
    #return etree.tostring(node).count(b'=')
    return sum(map(get_attr_number, node)) + len(node.attrib)

if __name__ == '__main__':
    sys.stdin.readline()
    xml = sys.stdin.read()
    tree = etree.ElementTree(etree.fromstring(xml))
    root = tree.getroot()
    print(get_attr_number(root))

Class 2 - Find the Torsional Angle

You are given four points  and  in a 3-dimensional Cartesian coordinate system. You are required to print the angle between the plane made by the points  and  in degrees(not radians). Let the angle be . 

 where  x  and  x .

Here,  means the dot product of  and , and  x  means the cross product of vectors  and . Also, .

Input Format

One line of input containing the space separated floating number values of the  and  coordinates of a point.

Output Format

Output the angle correct up to two decimal places.

Sample Input

0 4 5
1 7 6
0 5 9
1 7 2

Sample Output

8.19

import math

class Points(object):
    def __init__(self, x, y, z):
        self.x = float(x)
        self.y = float(y)
        self.z = float(z)

    def __add__(self, no):
        return Points(self.x + no.x, self.y + no.y, self.z + no.z)

    def __sub__(self, no):
        return Points(self.x - no.x, self.y - no.y, self.z - no.z)

    def dot(self, no):        
        return self.x * no.x + self.y * no.y + self.z * no.z

    def cross(self, no):
        return Points(self.y * no.z - self.z * no.y, self.z * no.x - self.x * no.z, self.x * no.y - self.y * no.x)
        
    def absolute(self):
        return pow((self.x ** 2 + self.y ** 2 + self.z ** 2), 0.5)

if __name__ == '__main__':
    points = list()
    for i in range(4):
        a = list(map(float, input().split()))
        points.append(a)

    a, b, c, d = Points(*points[0]), Points(*points[1]), Points(*points[2]), Points(*points[3])
    x = (b - a).cross(c - b)
    y = (c - b).cross(d - c)
    angle = math.acos(x.dot(y) / (x.absolute() * y.absolute()))

    print("%.2f" % math.degrees(angle))