[PYTHON] I don't want to take a coding test

I don't want to take a coding test

I will take a coding test, so make a note of it. I will make a note so I will update it. Please forgive me because it is a texto

2019/12/15 For the time being, I will do it with python that I usually use. Should I move to C ++ if I'm a competition pro?

2019/12/16 I want to solve the past questions of AtCoder For the time being, I made a repository on github. βshort repository

Competitive professional relationship?

paiza AOJ AtCoder

problem

1. AtCoder Beginners Selection
2. AtCoder problem

Reference & link

1. What to do next after registering with AtCoder-If you solve this much, you can fight enough! Past questions selected 10 questions ~
2. Cheat sheet for competitive programming used in Python
3. https://1kohei1.com/leetcode/
4. https://www.madopro.net/entry/2016/09/05/135126
5. https://www.freecodecamp.org/news/coding-interviews-for-dummies-5e048933b82b/
6. https://qiita.com/yohachi/items/e4bef4035da135a4808d
7. https://app.codility.com/programmers/lessons/1-iterations/
8. I tried to solve 10 selected past questions that should be solved after registering with AtCoder

Python notes

This is a memo related to grammar and numpy.

Input relationship

Reference: https://qiita.com/fmhr/items/77fc453e2fb1bc02e392

Multiple numbers to the specified variable

a, b, c, d = map(int, input().split())

List multiple numbers

#Input 1 3 4 5
a = [int(i) for i in input().split()] 
#a=[1 3 4 5]

List multiple strings

a = [i for i in input().split()] 

Output relation

Zero padded output

In case of multiple, specify by index For 2-digit decimal

#{Index number:Format specification}.format()
print("{0:02d}".format(1))
#01

No line breaks

print("Characters etc.", end='')

Decimal point

#Round up
math.ceil()
#Truncate
math.floor()
#Rounding
round()

n-ary

Binary: bin () Eighth number: oct () Hexadecimal: hex ()

match

All match'abc'=='abcd' is False Negation is! =

Partial match'abc' in'abcd' is True Negation is not in

String

How many'a' are in the string s

s.count('a')

s.replace("Before replacement", "After replacement")

I want to replace (assign) the character of the specified index

#String=>list
s = list("String")
s[2] = "formula"
s = "".join(s) 

list https://docs.python.org/ja/3/tutorial/datastructures.html To count the number of each element (the number of occurrences for each element), use the count () method.

a.append("Value you want to store")
a.remove("Value you want to delete")
a.pop()

List comprehension

[i for i in range(10)]

#ascending order
a.sort()
#descending order
a.sort(reverse=True)

sum(a)

map is an apply function in pandas

map(func, list)

set

a.add()
a.delete()

dict

numpy

np.zeros('shape')
np.ones('shape')
np.full('shape', 'value')

Number of elements in an array that meets the conditions

np.count_nonzero(a < 4)

Index of the maximum value of the array

#https://qiita.com/shippokun/items/01c85e36b8de7afd01a6

maxValue = np.max(a)
maxIndex = []
for i in range(len(a)):
    if maxVaule == a[i]:
        maxIndex.append(i)
print(maxIndex)    # [1, 4]

Conditional branching for each element of the numpy array

np.where(conditions, True, False))