Atcoder standard input set for beginners (python)

Introduction

I don't know how many brews anymore, but it is a summary of the standard input set for Atcoder.

I'm sloppy with Atcoder, but I haven't been devoted at all, so I can't remember the standard input forever. So, I would like to organize the standard input once and systematically organize the faster standard input.

This article summarizes the minimum standard input for solving the basic ABC-ABC problem in the basics. Standard input using sys and numpy will be covered in another article.

The pointed out part has been corrected (2020/05/06).

1 row 1 column data

input

N (string or number)

code

sample.py

#When receiving in str type
s = input() 
#When receiving as an int type
s = int(input()) 
#float type(Decimal)When receiving at
s = float(input())

As a caveat, note that input () is all str type, even if it is a number instead of a string.

(1, N) Matrix data

input

A B

If the input is a string

Input example

Alice Bob Charlie

** Code example 1 **

sample.py

#When receiving as list type
s = input().split()

#output
print(s)
>>['Alice', 'Bob', 'Charlie']
print(s[0])
>>Alice
print(s[0][0])
>>A

** Code example 2 **

sample.py

#When receiving as a string
A, B, C = input().split()

#output
print(A)    
>>Alice
print(A,B,C)
>>Alice Bob Charlie

If the input variable is an integer

Input example

1 3

** Code example 1 **

sample.py

A, B = map(int, input().split())

#output
print(A)
>>1
print(A,B)
>>1 3

When the number of input variables is N

input

A₁ A₂ A₃...A_N

Input example

1 3 4 5 6

** Code example 1 **

sample.py

#Get as list type
l = list(map(int, input().split()))

#output
print(l)
>>[1, 3, 4, 5, 6]

(N, 1) Matrix data

input

N M A₁ A₂ : A_N

Input example

3 4 2 3 3 1

** Code example 1 (int type) ** Convert (N, 1) matrix to (1, N) matrix by generating an empty list and storing it in the list in order from the top

sample.py

N, M = map(int, input().split())
#Empty list
A = []
#List A append()Store using
for _ in range(M):
    A.append(int(input())

#output
print(A)
>>[2, 3, 3, 1]

** Code example 2 (list comprehension) **

sample.py

N, M = map(int, input().split())
#List comprehension
A = [int(input()) for _ in range(M)]

#output
print(A)
>>[2, 3, 3, 1]

(N, M) Matrix data

2 variable data

When variables are lined up in a row

input

N x₁ x₂ x₃ .. x_N y₁ y₂ y₃ .. y_N

Input example

3 1 2 3 4 5 6

** Code example **

sample.py

N = int(input())
x = list(map(int, input().split()))
y = list(map(int, input().split()))

#output
print(x)
>>[1, 2, 3]

When variables are lined up in a column

input

N x₁ y₁ x₂ y₂ : x_N y_N

Input example

5 1 2 3 4 5 6 7 8 9 10

** Code example 1 (store x and y independently) **

sample.py

N = int(input())
xy = [map(int, input().split()) for _ in range(N)]
x, y = [list(i) for i in zip(*xy)]

#output
print(x)
>>[1, 3, 5, 7, 9]
print(x[1]+y[1])
>>7

** Code example 2 (stored as [x _{i </ sub>, y i </ sub>]) **}

sample.py

N = int(input())
l = [list(map(int, input().split())) for l in range(N)]

#output
print(l)
>>[[1, 2], [3, 4], [5, 6]]

** In case of mixed int type and str type **

Input example

5 1 a 3 b 5 c 7 d 9 e

sample.py

N = int(input())
list = []
for i in range(N):
    a,b=input().split()
    list.append([int(a), b])
    
#output
print(list)
>>[[1, 'a'], [3, 'b'], [5, 'c'], [7, 'd'], [9, 'e']]
print(type(list[0][0]))
>><class'int'>
print(type(list[0][1]))
>><class'str'>

It was very easy to understand, so I quoted it from this article. Standard input of python3 in competition professionals

3 variable data

input

N t₁ x₁ y₁ t₂ x₂ y₂ : t_N x_N y_N

Input example

2 3 1 2 6 1 1

sample.py

#First, create a list with the length of the input variable. * N=In case of 5,t = [0,0,0,0,0]
N = int(input())
t = [0] * N
x = [0] * N
y = [0] * N
for i in range(N):
    #Substitute in order from the top
    t[i], x[i], y[i] = map(int, input().split())

#output
print(t)
>>[3, 6]

I quoted from this article Tips you should know when programming in Python3 (input)

3 Variable data (when the number of data is different for each variable)

input

X Y A B C P₁ P₂ P₃...P_A Q₁ Q₂ Q₃...Q_B R₁ R₂ R₃...R_C

Problem: E --Red and Green Apples

Input example

1 2 2 2 1 2 4 5 1 3

sample.py

X, Y, A, B, C = map(int, input().split())
P = [int(i) for i in input().split()]
Q = [int(i) for i in input().split()]
R = [int(i) for i in input().split()]

#output
print(P)
>>[2, 4]

#There is no problem with this form
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
R = list(map(int, input().split()))

General matrix data

input

N M A_1,1 A_1,2...A_{1 ,N} : A_M,1 A_M,2...A_M,N

** Input example (3,3) Matrix data **

3 3 2 1 3 1 3 3 2 2 1

** Code example 1 (int type) **

sample.py

N, M = map(int,input().split()) 
#List comprehension
#Read the list in order from the top and store it in the list.
a = [list(map(int, input().split())) for l in range(M)]

#output
print(a)
>>[[2, 1, 3], [1, 3, 3], [2, 2, 1]]

print(a[0])
>>[2, 1, 3]
print(a[0][0])
>>2
print(type(a[0][0]))
>><class'int'>

Supplement -numpy-

A little introduction to ** numpy **. You can use ** numpy ** to convert a list to a ** numpy array ndarray **. By performing this conversion, not only matrix operations can be performed, but also execution speed can be increased and code can be simplified.

sample.py

import numpy as np
#Appropriate list
list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

#Convert to ndarray
list_ndarray = np.array(list)
print(list_ndarray)
>>[[1 2 3]
   [4 5 6]
   [7 8 9]]

#Array size(Element count)
print(list_ndarray.size)
>>9
#Array shape
print(list_ndarray.shape)
>>(3, 3)
#Mold
print(type(list_ndarray))
>><class'numpy.ndarray'>

#numpy array → list
list_list = list_ndarray.tolist()
print(list_list)
>>[[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(type(list_list))
>><class'list'>

Articles that I used as a reference

-[Standard input in python3] (https://qiita.com/pyu666/items/6b8cfefc1ea994639683) ・ Tips you should know when programming in Python3 (input) -Standard input of python3 in competition pros, etc. ・ Python de Competitive Programming

About standard input and standard output

See the article below for details. ・ [What are standard input and standard output? ] (https://qiita.com/angel_p_57/items/03582181e9f7a69f8168)

Make corrections as appropriate.

Continue to another article.