Disclaimer: ICPC国内予選仕様です。速度/メモリの面でのパフォーマンスは考慮しません

入力編

一行の入力を受け付ける場合、こう書きます

input()

整数への変換は int(s) を使います

n = int(input())

一行に空白文字区切りの複数の入力を受け付ける場合、こう書きます

a, b = input().split()

一行に複数の整数の入力を受け付ける場合、こう書きます

a, b = [int(w) for w in input().split()]

line = input()
print("'" + line + "'")

words = line.split()
print(words)

integers = [int(w) for w in words]
print(integers)

a, b = integers
# a, b = [int(w) for w in input().split()]
print(a, b)

6 9
'6 9'
['6', '9']
[6, 9]
6 9

N = int(input())
mat = []
for i in range(N):
    mat.append([int(w) for w in input().split()])
print(mat)

3
1 2 3
4 5 6
7 8 9
[[1, 2, 3], [4, 5, 6], [7, 8, 9]]

help(str.split)

Help on method_descriptor:

split(...)
    S.split(sep=None, maxsplit=-1) -> list of strings
    
    Return a list of the words in S, using sep as the
    delimiter string.  If maxsplit is given, at most maxsplit
    splits are done. If sep is not specified or is None, any
    whitespace string is a separator and empty strings are
    removed from the result.

セパレータ sep を指定しないと空白文字区切りで返ってきます

# リスト内包表記使わず書くとこんな感じ
list(map(int, input().split()))

1 2 3
[1, 2, 3]

出力編

print("Hello world")
print(1, 2, 3)
print("%d, %d" % (1, 2))
print("{}: {} ({})".format("key", "value", 3))

Hello world
1 2 3
1, 2
key: value (3)

文字列のフォーマットに関して

a, b = 1, 2
print("a: %d, b: %d" % (a, b))
# for >= 3.6
# print(f"a: {a}, b: {b}")

a: 1, b: 2

なお、剰余演算も % を用います。別の演算に同じ記号を割り当てるのは悪い文明です。

print(777 % (7 * 7))

42

改行なしはどうやるの？

for i in range(10):
    print("%d " % i, end='')
print()

0 1 2 3 4 5 6 7 8 9 

" ".join(map(str, range(10)))

'0 1 2 3 4 5 6 7 8 9'

help(print)

Help on built-in function print in module builtins:

print(...)
    print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
    
    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file:  a file-like object (stream); defaults to the current sys.stdout.
    sep:   string inserted between values, default a space.
    end:   string appended after the last value, default a newline.
    flush: whether to forcibly flush the stream.

print(1, 2, 3, 4, sep=",\t")

1,	2,	3,	4