Buildins from Hackerrank
Study notes about Buildins
Zip
zip([iterable, …])
This function returns a list of tuples. The (i)th tuple contains the (i)th element from each of the argument sequences or iterables.
If the argument sequences are of unequal lengths, then the returned list is truncated to the length of the shortest argument sequence.
- Example:
Task
The National University conducts an examination of N students in X subjects. Your task is to compute the average scores of each student.
Average score = (sum of scores obtained in all subjects by a student)/ (Total number of subjects)
The format for the general mark sheet is:
| Student ID | 1 2 3 4 5 |
| Subject 1 | 89 90 78 93 80 |
| Subject 2 | 90 91 85 88 86 |
| Subject 3 | 91 92 83 89 90.5 |
| Average | 90 91 82 90 85.5 |
Input Format
The first line contains N and X separated by a space. The next X lines contains the space separated marks obtained by students in a particular subject.
Constraints
0 < N <= 100
0 < X <= 100
Output Format
Print the averages of all students on separate lines.
The averages must be correct up to 1 decimal place.
N, X = map(int, raw_input().split())
subjects = list()
for i in range(0, X):
subjects.append(list(map(float, raw_input().split())))
students = zip(*subjects)
for i in range(0, N):
marks = 0.0
for j in range(0, X):
marks += students[i][j]
print marks / X
input:
5 3
89 90 78 93 80
90 91 85 88 86
91 92 83 89 90.5
output:
90.0
91.0
82.0
90.0
85.5
https://www.hackerrank.com/challenges/zipped
eval
The eval() expression is a very powerful built-in function of Python. It helps in evaluating an expression. The expression can be a Python statement, or a code object.
For example:
>>> eval("9 + 5")
14
>>> x = 2
>>> eval("x + 3")
5
Here, eval() can also be used to work with Python keywords or defined functions and variables. These would normally be stored as strings.
For example:
>>> type(eval("len"))
<type 'builtin_function_or_method'>
Without eval()
>>> type("len")
<type 'str'>
Task You are given an expression in a line. Read that line as a string variable, such as var, and print the result using eval(var).
NOTE: Python2 users, please import from _ _future__ import print_function.
Constraint Input string is less than 100 characters.
- Code:
from __future__ import print_function
x = str(raw_input())
eval(x)
input:
print (2+4)
output:
6
https://www.hackerrank.com/challenges/python-eval
reduce
- Example: You are given a string S. S contains alphanumeric characters only. Your task is to sort the string S in the following manner:
All sorted lowercase letters are ahead of uppercase letters. All sorted uppercase letters are ahead of digits. All sorted odd digits are ahead of sorted even digits. Input Format
A single line of input contains the string S.
Constraints
0<len(S) < 1000
Output Format
Output the sorted string S.
from string import ascii_lowercase, ascii_uppercase
order = ascii_lowercase + ascii_uppercase + "1357902468"
print (reduce(lambda x,y: x+y, sorted(raw_input(), key=order.index)))
input:
Sorting1234
output:
ginortS1324