Good Input Template for Python Users for Quick and Fast Inputs

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Hello Codeforces Community,

Actually all of the Python users over here would agree that "sometimes" we need to write a bit long for taking input in Python, and it is also slow.

That's why I made a good template for taking Quick And Fast Input, which I would like to share.

import sys
input = sys.stdin.readline

############ ---- Input Functions ---- ############
def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))

Just paste this template at the beginning of your Code.

It comprises of 4 functions :-

1) inp — For taking integer inputs.

2) inlt — For taking List inputs.

3) insr — For taking string inputs. Actually it returns a List of Characters, instead of a string, which is easier to use in Python, because in Python, Strings are Immutable.

4) invr — For taking space seperated integer variable inputs.

The input = sys.stdin.readline is actually for Faster Inputs, because line reading through System STDIN (Standard Input) is faster in Python.

# ENTER YOUR DETAILS HERE --------------------> ''' // -- Template by A_*_A -- // ''' # <---------------------------------------- # ENTER YOUR CODE HERE --------------------> # sys.setrecursionlimit(1000) ''' # 0.7 sec average INTEST - best for Codechef import atexit,io,os,sys ss=io.BytesIO() _write=ss.write ss.write=lambda s:_write(s.encode()) atexit.register(lambda:os.write(1,ss.getvalue())) y_in=open(0).read().split("\n") def y_inf(): for y_id in range(len(y_in)): yield y_id y_ino=y_inf() input=lambda:y_in[next(y_ino)] # ''' ''' # 1.1 sec average INTEST import sys input=sys.stdin.readline # input=lambda:sys.stdin.readline().rstrip("\r\n") # ''' # ''' # REGION FASTIO 1.7 sec average INTEST - best for Codeforces import os,sys from io import BytesIO,IOBase BUFSIZ=8192 class FastIO(IOBase): newlines=0 def __init__(self,file): self._fd=file.fileno() self.buffer=BytesIO() self.writable="n"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,BUFSIZ)) 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, BUFSIZ)) 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") if sys.version_info[0]<3: sys.stdin,sys.stdout=FastIO(sys.stdin),FastIO(sys.stdout) else: sys.stdin,sys.stdout=IOWrapper(sys.stdin),IOWrapper(sys.stdout) input=lambda:sys.stdin.readline().rstrip("\r\n") # END REGION ''' # 2.1 sec average INTEST tcs = 1 # tcs = int(input()) for tc in range(tcs): print("Hello World!") # <---------------------------------------- # ENTER YOUR NOTES HERE --------------------> ''' // -- Template by A_*_A -- // ''' # <----------------------------------------

# ''' # 0.65 sec - NOTE: ONLY SEND STRINGS TO STDOUT import atexit, io, os inputt = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline # read STDIN in 1 go input = lambda: inputt() # use for integer input # input = lambda: inputt().decode().strip() # use for string input ss = io.BytesIO() _write = ss.write ss.write = lambda s: _write(s.encode()) # byte text optimization atexit.register(lambda: os.write(1, ss.getvalue())) # os.write is fast!!! print=ss.write # END REGION '''

# ''' # FASTIO BEGINS 0.34 sec # FASTIO ENDS ''' import sys;k=int(sys.stdin.readline().split()[1]);sys.stdout.write('%d'%sum(1 for x in map(int,sys.stdin.buffer) if not x%k)) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 0.37 sec import sys # FASTIO ENDS ''' _, k = map(int, sys.stdin.readline().split()) count = sum(1 for x in map(int, sys.stdin.buffer) if not x % k) sys.stdout.write(str(count)) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 0.64 sec import sys input=sys.stdin.readline # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 0.65 sec import atexit, io, os inputt = io.BytesIO(os.read(0, os.fstat(0).st_size)).readline input = lambda: inputt() # int # input = lambda: inputt().decode().strip() # str ss = io.BytesIO() _write = ss.write ss.write = lambda s: _write(s.encode()) atexit.register(lambda: os.write(1, ss.getvalue())) # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 0.87 sec import sys input=lambda:sys.stdin.readline() # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 0.94 sec import atexit,io,os,sys ss=io.BytesIO() _write=ss.write ss.write=lambda sett:_write(sett.encode()) atexit.register(lambda:os.write(1,ss.getvalue())) y_in=open(0).read().split("\n") def y_inf(): for y_id in range(len(y_in)): yield y_id y_ino=y_inf() input=lambda:y_in[next(y_ino)] # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 1.08 sec import sys input=lambda:sys.stdin.readline().rstrip("\r\n") # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 1.8 sec import os,sys from io import BytesIO,IOBase BUFSIZ=8192 class FastIO(IOBase): newlines=0 def __init__(self,file): self._fd=file.fileno() self.buffer=BytesIO() self.writable="n"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,BUFSIZ)) 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, BUFSIZ)) 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 sett:self.buffer.write(sett.encode("ascii")) self.read=lambda:self.buffer.read().decode("ascii") self.readline=lambda:self.buffer.readline().decode("ascii") if sys.version_info[0]<3: sys.stdin,sys.stdout=FastIO(sys.stdin),FastIO(sys.stdout) else: sys.stdin,sys.stdout=IOWrapper(sys.stdin),IOWrapper(sys.stdout) input=lambda:sys.stdin.readline().rstrip("\r\n") # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c) ---------------------------------------------------------------- # ''' # FASTIO BEGINS 2.1 sec # FASTIO ENDS ''' y0, y1 = [int(x) for x in input().split()] c = sum(not int(input()) % y1 for i in range(y0)) print(c)

Comments (9)

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ouuan

5 years ago, # |

This blog may be useful.

→ Reply

KimLikeAStone

Thank You! This is so useful!

violist

4 years ago, # |

← Rev. 2 →

Hi, I just want to ask when to use sys.stdin.readline, because once I used it and it gave me wrong output (WA) and when I removed it, my code was Accepted. Here are my submissions:

With sys.stdin.readline: 108547882 Without: 108548171

aryanc403

4 years ago, # ^ |

sys.stdin.readline also reads end of line "\n" character. See here vs here

Also, note how does the blog takes string input in insr() function. It explicitly removes the last character.

vaishnavigogineni111

2 years ago, # |

can anyone share the full template for Python please

blackhatinside

2 years ago, # ^ |

I won't say my template is the best out there for Python. But I think it might be of some use to you. Sharing it below, I have made separate ones for both Codechef and Codeforces. Here you go. Hope you find it helpful :)

0_0perplexed

@a_vantik_a Thanks! though I need to understand it all, looks daunting. Do you've a blog or something of that sort explaining it in chunks? Would be of big BIG help !

Hey, you are welcome. I am glad you found it helpful :) I have added commments to the code below, to make it a bit easy to understand. In case you want more reference or meaning about the code, you can simply google it. I referred a lot of blogs to come up with this FASTIO :)

Have a good day, cheers!

I know using Python in Codeforces on a long term basis isn't really a good idea. But I am doing it for my own research reasons. Here is the whole list of FASTIO Comparisons I did for Python3, to come up with the best case for both Codechef and Codeforces, results were taken using best of 3 runs for each template. Hope you find it helpful :)

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