HackerRank XML2 Find the Maximum Depth solution in python

In this XML2 find the maximum depth problem, 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 0.

Problem solution in Python 2 programming.

# Enter your code here. Read input from STDIN. Print output to STDOUT
def depth(tree):
    dp = 0
    if tree is not None:
        for i in tree:
            dp = max(dp,  depth(i) + 1)
    return dp
n = int(raw_input())
xml = ""
for i in range(n):
    xml += raw_input()
import xml.etree.ElementTree as etree
tree = etree.fromstring(xml)


print depth(tree)

Problem solution in Python 3 programming.

global maxdepth
maxdepth = -1
def depth(elem, level):
    global maxdepth
    if (level == maxdepth):
        maxdepth += 1
        
    for child in elem:
        depth(child, level + 1)

Problem solution in pypy programming.

maxdepth = 0
def depth(elem, level):
    global maxdepth
    
    if (level == maxdepth):
        maxdepth += 1
        
    for child in elem:
        depth(child, level + 1)

Problem solution in pypy3 programming.

maxdepth = 0
def depth(elem, level):
    global maxdepth

    for child in elem:
        depth(child, level+1)
        maxdepth = max(maxdepth, level+2)