优秀代码样板收集计划（python）
- 快速输出
- dfs,thread,python3,defaultdict,换根dp
- Counter,元组map
- 捕获异常
- 数组排序翻转切片
- bfs
- accumulate
- 二维数组读入，math库调用
- 字符串
- counter数组
- bisect（lower_bound upper_bound）
- 列表推导式
输出
sys.stdout.write(" ".join(map(str,ans))+"\n")
dfs,bootstrap ，换根DP
import os
import sys
from io import BytesIO, IOBase
from types import GeneratorType
from collections import defaultdict
BUFSIZE = 8192
class FastIO(IOBase):
newlines = 0
def __init__(self, file):
self._fd = file.fileno()
self.buffer = BytesIO()
self.writable = "x" in file.mode or "r" not in file.mode
self.write = self.buffer.write if self.writable else None
def read(self):
while True:
b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
if not b:
break
ptr = self.buffer.tell()
self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
self.newlines = 0
return self.buffer.read()
def readline(self):
while self.newlines == 0:
b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
self.newlines = b.count(b"\n") + (not b)
ptr = self.buffer.tell()
self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
self.newlines -= 1
return self.buffer.readline()
def flush(self):
if self.writable:
os.write(self._fd, self.buffer.getvalue())
self.buffer.truncate(0), self.buffer.seek(0)
class IOWrapper(IOBase):
def __init__(self, file):
self.buffer = FastIO(file)
self.flush = self.buffer.flush
self.writable = self.buffer.writable
self.write = lambda s: self.buffer.write(s.encode("ascii"))
self.read = lambda: self.buffer.read().decode("ascii")
self.readline = lambda: self.buffer.readline().decode("ascii")
sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")
sys.setrecursionlimit(2 * 10 ** 5)
ans=0
def bootstrap(f, stack=[]):
def wrappedfunc(*args, **kwargs):
if stack:
return f(*args, **kwargs)
else:
to = f(*args, **kwargs)
while True:
if type(to) is GeneratorType:
stack.append(to)
to = next(to)
else:
stack.pop()
if not stack:
break
to = stack[-1].send(to)
return to
return wrappedfunc
@bootstrap
def dfs(now, lay, fa):
SUM[now] = 0
NUM[now] = C[now]
for to in A[now]:
if to != fa:
yield dfs(to, lay + 1, now)
SUM[now] += SUM[to]
SUM[now] += NUM[to]
NUM[now] += NUM[to]
yield
@bootstrap
def change(now, fa):
global ans
ans = max(ans, SUM[now])
for to in A[now]:
if to != fa:
SUM[now] -= SUM[to]
SUM[now] -= NUM[to]
NUM[now] -= NUM[to]
NUM[to] += NUM[now]
SUM[to] += SUM[now]
SUM[to] += NUM[now]
yield change(to, now)
SUM[to] -= SUM[now]
SUM[to] -= NUM[now]
NUM[to] -= NUM[now]
NUM[now] += NUM[to]
SUM[now] += SUM[to]
SUM[now] += NUM[to]
yield
n = int(input())
A = [[] for i in range(n + 1)]
C = [0] + (list(map(int, input().split())))
NUM = [0] * (n + 1)
SUM = [0] * (n + 1)
for i in range(n - 1):
x, y = map(int, input().split())
A[x].append(y)
A[y].append(x)
dfs(1, 0, 0)
change(1, 0)
print(ans)
# print(NUM)
# print(SUM)
dfs,thread,python3,defaultdict,换根dp
from collections import defaultdict
import threading
import sys
input = sys.stdin.readline
sys.setrecursionlimit(10**6)
threading.stack_size(10**8)
'''
n, m = map(int, input().split())
n = int(input())
A = list(map(int, input().split()))
S = input().strip()
for CASES in range(int(input())):
'''
inf = 100000000000000000 # 1e17
mod = 998244353
A = defaultdict(list)
son = defaultdict(int)
dp = defaultdict(int)
n = int(input())
for CASES in range(n - 1):
x, y = map(int, input().split())
A[x].append(y)
A[y].append(x)
def dfs1(now, fa): # get son
son[now] = 1
for to in A[now]:
if to == fa:
continue
dfs1(to, now)
son[now] += son[to]
def dfs2(now, fa): # get dp
dp[now] = son[now]
for to in A[now]:
if to == fa:
continue
dfs2(to, now)
dp[now] += dp[to]
def dfs3(now, fa): # transfer
global ans
ans = max(ans, dp[now])
for to in A[now]:
if to == fa:
continue
dp[now] -= dp[to] + son[to]
dp[to] += dp[now] + (n - son[to])
dfs3(to, now)
dp[to] -= dp[now] + (n - son[to])
dp[now] += dp[to] + son[to]
def main():
dfs1(1, 0)
dfs2(1, 0)
dfs3(1, 0)
ans = 0
t = threading.Thread(target=main)
t.start()
t.join()
print(ans)
counter
from collections import Counter
import sys
input = sys.stdin.readline
'''
n, m = map(int, input().split())
n = int(input())
A = list(map(int, input().split()))
S = input().strip()
for CASES in range(int(input())):
'''
inf = 100000
mod = 998244353
def fac(x):
i = 2
while i * i <= x:
if x % i == 0:
cnt = 0
while x % i == 0:
cnt += 1
x //= i
cnt %= k
if cnt > 0:
sig.append((i, cnt))
i += 1
if x > 1:
sig.append((x, 1))
n, k = map(int, input().split())
A = list(map(int, input().split()))
ans = 0
prev = Counter()
for a in A:
sig = []
fac(a)
com_sig = []
for p, val in sig:
com_sig.append((p, k - val))
ans += prev[tuple(sig)]
prev[tuple(com_sig)] += 1
print(ans)
try
try:
n = int(v)
except Exception as e:
print("Couldn't parse")
print('Reason:', e)
数组排序切片
import sys
input = sys.stdin.readline
'''
n, m = map(int, input().split())
n = int(input())
A = list(map(int, input().split()))
for test in range(int(input())):
'''
inf = 100000000000000000 # 1e17
x, y, a, b, c = map(int, input().split())
array_a = list(map(int, input().split()))
array_b = list(map(int, input().split()))
array_c = list(map(int, input().split()))
array_a = sorted(array_a, reverse=True)[:x]
array_b = sorted(array_b, reverse=True)[:y]
ans = sum(sorted(array_a + array_b + array_c, reverse=True)[:x + y])
print(ans)
bfs
from itertools import accumulate
from collections import deque
def bfs(STA):
DIS = [-1] * (n + 1)
Q = deque([STA])
DIS[STA] = 0
while Q:
x = Q.pop()
for to in A[x]:
if DIS[to] == -1:
DIS[to] = DIS[x] + 1
Q.appendleft(to)
return DIS
accumulate
input = sys.stdin.readline
from itertools import accumulate
t=int(input())
for tests in range(t):
n,k=map(int,input().split())
A=list(map(int,input().split()))
ANS=[0]*(k*2+3)
for i in range(n//2):
x,y=A[i],A[n-1-i]
if x>y:
x,y=y,x
#print(x,y)
ANS[x+1]-=1
ANS[y+k+1]+=1
ANS[x+y]-=1
ANS[x+y+1]+=1
#print(ANS)
#print(ANS)
S=list(accumulate(ANS))
#print(S)
print(n+min(S))
二维数组读入，math库调用
# https://codeforces.com/contest/1220/problem/B
import sys
input=sys.stdin.readline
n=int(input())
A=[list(map(int,input().split())) for i in range(n)]
from math import ceil,sqrt
ANS=[]
tmp=A[0][1]*A[0][2]//A[1][2]
ANS.append(ceil(sqrt(tmp)))
for i in range(1,n):
ANS.append(A[0][i]//ANS[0])
print(*ANS)
字符串
import sys
input=sys.stdin.readline
n=input()
S=input().strip()
one=S.count("n")
zero=S.count("z")
ANS=[1]*one+[0]*zero
print(*ANS)
Counter数组
https://codeforces.com/contest/1208/problem/B
import sys
input=sys.stdin.readline
n=int(input())
A=list(map(int,input().split()))
from collections import Counter
import copy
C=Counter(A)
for a in A:
if C[a]<=1:
del C[a]
if not(C):
print(0)
sys.exit()
ans=n-1
for i in range(n):
D=copy.deepcopy(C)
for j in range(i,n):
if D[A[j]]>1:
D[A[j]]-=1
if D[A[j]]==1:
del D[A[j]]
if not(D):
ans=min(ans,j-i+1)
break
print(ans)
bisect
import bisect
L = [1,3,3,3,6,8,12,15]
x = 3
x_insert_point = bisect.bisect_left(L,x)
print (x_insert_point)
x_insert_point = bisect.bisect_right(L,x)
print(x_insert_point)
列表推导式
# https://codeforces.com/contest/1332/problem/C
def f(l):
d={}
for i in l:
if i in d:
d[i]+=1
else:
d[i]=1
return len(l)-max(d.values())
import sys
for _ in range(int(sys.stdin.readline())):
n,k=map(int,sys.stdin.readline().split())
s=input()
print(sum(f(s[j::k]+s[k-j-1::k]) for j in range(k//2))+sum(f(s[k//2::k]) for j in range(k%2)))
进制转换
def toshi(x):
if '0'<=x<='9':
return ord(x)-48
return ord(x)-ord('a')+10
def shito(x):
if 0<=x<=9:
return chr(x+48)
return chr(x-10+ord('a'))
s=input()
a,b=map(int,input().split())
ans=0
for i in s:
ans*=a
ans+=toshi(i)
if ans==0:
print(0)
pr=''
while ans>0:
pr=shito(ans%b)+pr
ans//=b
print(pr)
初始化数组并设两边为无穷大
A[0]=float("inf")
A[n+1]=float("inf")
交互问题输出
print("?",mid,flush=True)
