AtCoder Beginner Contest 245


A - Good morning

import sys
import heapq, math, itertools
from collections import defaultdict, deque
from bisect import bisect_left, bisect_right, insort_left, insort_right
inputs = sys.stdin.readline
mod = 10**9+7
inf = float('inf')
#sys.setrecursionlimit(10**7)

def main():
  a,b,c,d = map(int, inputs().split())
  print('Takahashi' if a*60+b<=c*60+d else 'Aoki')

if __name__ == '__main__':
  main()

Aoki君は1秒後に起きているということは、A==C,B==DのときTakahashi君の方が早く起きているということです

B - Mex

import sys
import heapq, math, itertools
from collections import defaultdict, deque
from bisect import bisect_left, bisect_right, insort_left, insort_right
inputs = sys.stdin.readline
mod = 10**9+7
inf = float('inf')
#sys.setrecursionlimit(10**7)

def main():
  n = int(input())
  a = list(map(int, inputs().split()))
  for i in range(2001):
    if i not in set(a):
      print(i)
      exit()

if __name__ == '__main__':
  main()

Nが高々2000程度なので候補となる値を全探索すればよさそうです
集合型を使うことで高速に判定しましょう。

C - Choose Elements

import sys
import heapq, math, itertools
from collections import defaultdict, deque
from bisect import bisect_left, bisect_right, insort_left, insort_right
from xmlrpc.client import FastMarshaller
inputs = sys.stdin.readline
mod = 10**9+7
inf = float('inf')
#sys.setrecursionlimit(10**7)

def main():
  n,k = map(int, inputs().split())
  a = list(map(int, inputs().split()))
  b = list(map(int, inputs().split()))
  lst = [a[0], b[0]]
  flg = True
  for i in range(1, n):
    if not lst:
      flg = False
      break
    else:
      nxt = []
      for x in lst:
        if abs(x-a[i])<=k:
          nxt.append(a[i])
        if abs(x-b[i])<=k:
          nxt.append(b[i])
      lst = list(set(nxt))
  if not lst:
    flg = False
  print('Yes' if flg else 'No')

if __name__ == '__main__':
  main()

1つ1つシミュレーションしてあげればよさそうです。
X_i-1の候補となる値に対してA_iB_iが許容されるか、ということを判定します。
候補となるX_iが無いとき、数列Xが存在できないということとなります。
またX_iの候補となる値を探索するとき、数の重複が無いように注意しましょう。
これをケアしないと際限なく候補の数が増えてしてしまいTLEとなります。

D - Polynomial division

import sys
import numpy as np
import heapq, math, itertools
from collections import defaultdict, deque
from bisect import bisect_left, bisect_right, insort_left, insort_right
inputs = sys.stdin.readline
mod = 10**9+7
inf = float('inf')
#sys.setrecursionlimit(10**7)

def main():
  n,m = map(int, inputs().split())
  a = list(map(int, inputs().split()))
  c = list(map(int, inputs().split()))
  pa = np.poly1d(a[::-1])
  pc = np.poly1d(c[::-1])
  p,q = np.polydiv(pc,pa)
  p = np.array(p).astype('int')
  print(*list(p)[::-1])

if __name__ == '__main__':
  main()

numpyは便利です...!
pythonを使う大きなメリットの1つなので、このような学術的(?)なものはnumpyで簡単に解決できないかということを検討するとよい場合があります

E - Wrapping Chocolate

import sys
import heapq, math, itertools
from collections import defaultdict, deque
from bisect import bisect_left, bisect_right, insort_left, insort_right, insort
inputs = sys.stdin.readline
mod = 10**9+7
inf = float('inf')
#sys.setrecursionlimit(10**7)
from typing import Generic, Iterable, Iterator, TypeVar, Union, List
T = TypeVar('T')

class SortedMultiset(Generic[T]):
    BUCKET_RATIO = 50
    REBUILD_RATIO = 170

    def _build(self, a=None) -> None:
        "Evenly divide `a` into buckets."
        if a is None: a = list(self)
        size = self.size = len(a)
        bucket_size = int(math.ceil(math.sqrt(size / self.BUCKET_RATIO)))
        self.a = [a[size * i // bucket_size : size * (i + 1) // bucket_size] for i in range(bucket_size)]
    
    def __init__(self, a: Iterable[T] = []) -> None:
        "Make a new SortedMultiset from iterable. / O(N) if sorted / O(N log N)"
        a = list(a)
        if not all(a[i] <= a[i + 1] for i in range(len(a) - 1)):
            a = sorted(a)
        self._build(a)

    def __iter__(self) -> Iterator[T]:
        for i in self.a:
            for j in i: yield j

    def __reversed__(self) -> Iterator[T]:
        for i in reversed(self.a):
            for j in reversed(i): yield j
    
    def __len__(self) -> int:
        return self.size
    
    def __repr__(self) -> str:
        return "SortedMultiset" + str(self.a)
    
    def __str__(self) -> str:
        s = str(list(self))
        return "{" + s[1 : len(s) - 1] + "}"

    def _find_bucket(self, x: T) -> List[T]:
        "Find the bucket which should contain x. self must not be empty."
        for a in self.a:
            if x <= a[-1]: return a
        return a

    def __contains__(self, x: T) -> bool:
        if self.size == 0: return False
        a = self._find_bucket(x)
        i = bisect_left(a, x)
        return i != len(a) and a[i] == x

    def count(self, x: T) -> int:
        "Count the number of x."
        return self.index_right(x) - self.index(x)

    def add(self, x: T) -> None:
        "Add an element. / O(√N)"
        if self.size == 0:
            self.a = [[x]]
            self.size = 1
            return
        a = self._find_bucket(x)
        insort(a, x)
        self.size += 1
        if len(a) > len(self.a) * self.REBUILD_RATIO:
            self._build()

    def discard(self, x: T) -> bool:
        "Remove an element and return True if removed. / O(√N)"
        if self.size == 0: return False
        a = self._find_bucket(x)
        i = bisect_left(a, x)
        if i == len(a) or a[i] != x: return False
        a.pop(i)
        self.size -= 1
        if len(a) == 0: self._build()
        return True

    def lt(self, x: T) -> Union[T, None]:
        "Find the largest element < x, or None if it doesn't exist."
        for a in reversed(self.a):
            if a[0] < x:
                return a[bisect_left(a, x) - 1]

    def le(self, x: T) -> Union[T, None]:
        "Find the largest element <= x, or None if it doesn't exist."
        for a in reversed(self.a):
            if a[0] <= x:
                return a[bisect_right(a, x) - 1]

    def gt(self, x: T) -> Union[T, None]:
        "Find the smallest element > x, or None if it doesn't exist."
        for a in self.a:
            if a[-1] > x:
                return a[bisect_right(a, x)]

    def ge(self, x: T) -> Union[T, None]:
        "Find the smallest element >= x, or None if it doesn't exist."
        for a in self.a:
            if a[-1] >= x:
                return a[bisect_left(a, x)]
    
    def __getitem__(self, x: int) -> T:
        "Return the x-th element, or IndexError if it doesn't exist."
        if x < 0: x += self.size
        if x < 0: raise IndexError
        for a in self.a:
            if x < len(a): return a[x]
            x -= len(a)
        raise IndexError

    def index(self, x: T) -> int:
        "Count the number of elements < x."
        ans = 0
        for a in self.a:
            if a[-1] >= x:
                return ans + bisect_left(a, x)
            ans += len(a)
        return ans

    def index_right(self, x: T) -> int:
        "Count the number of elements <= x."
        ans = 0
        for a in self.a:
            if a[-1] > x:
                return ans + bisect_right(a, x)
            ans += len(a)
        return ans

def main():
  n,m = map(int, inputs().split())
  a = list(map(int, inputs().split()))
  b = list(map(int, inputs().split()))
  c = list(map(int, inputs().split()))
  d = list(map(int, inputs().split()))
  tot = []
  for i in range(n):
    tot.append((a[i], b[i], 0))
  for i in range(m):
    tot.append((c[i], d[i], 1))
  tot = sorted(tot, reverse=True)
  flg = True
  cand = SortedMultiset()
  for i,j,k in tot:
    if k==1:
      cand.add(j)
    else:
      ele = cand.ge(j)
      if ele==None:
        flg = False
        break
      else:
        cand.discard(ele)
  print('Yes' if flg else 'No')
if __name__ == '__main__':
  main()

この問題の難しいポイントは、縦と横の長さの両方を比較・管理しなければいけないところにあると思います。そこで縦の長さか横の長さでソートしてしまえば、比較する方向が1つに減らすことができそうです。(同じ長さの場合は箱を優先することに注意しましょう)

よって問題は「チョコの横幅以上の箱の数が足りているか」という問題に帰着するので、MultiSetを使ってACです。