Python is a very friendly language,The only downside is the slow speed.與 C、C++ 和 Java 相比,它要慢得多.Online coding platform,如果提供的 C/C++ 限制為X.通常,在 Java The time provided in is2X和 Python,它是5X.
To improve input/Code execution speed for output-intensive problems,Languages have various input and output processes.\
示例問題：
Consider looking for user input 的Nthe sum of numbers.
輸入一個數字N.
輸入的Nnumbers are separated by a single space on a line. \
例子：
輸入 ：
5
1 2 3 4 5
輸出 ：
15
different from the above problems Python 解決方案：
普通方法 Python：（Python 2.7）
1. raw_input() Takes an optional prompt parameter.It also strips trailing newlines from the string it returns.
2. printJust a thin wrapper,It formats the input（args and the trailing newline）並調用給定對象的 write 函數.
# Basic method of input and output
# 輸入 N
n = int(input())
# 輸入數組
arr = [int(x) for x in input().split()]
# 初始化變量
summation = 0
# 計算總和
for x in arr:
summation += x
# 輸出答案
print(summation)
Faster method using built-in standard input,標准輸出：（Python 2.7）
1.另一方面, sys.stdin是File Object.This is just like creating any other file object that can be created to read input from a file.在這種情況下,file will be the standard input buffer.
2. stdout.write('D\n') 比print 'D' 快.
3. Faster is throughstdout.write(“”.join(list-comprehension))
寫入一次,But this makes memory usage dependent on the size of the input.
# Import built-in standard input and output
from sys import stdin, stdout
# 假設有一個名為 main() 的函數,and all operations have been performed
def main():
# 通過 readline 方法輸入
n = stdin.readline()
# Array input is similar
arr = [int(x) for x in stdin.readline().split()]
#初始化變量
summation = 0
# 計算總和
for x in arr:
summation += x
# The built-in summation can be used = sum(arr)
# 通過 write 打印答案
# write The method only writes string operations
# So we need to convert any data to string as input
stdout.write(str(summation))
# 調用主方法
if __name__ == "__main__":
main()
時間上的區別：
Timing summary (100k lines each) ——————————– Print : 6.040 s Write to file : 0.122 s Print with Stdout : 0.121 s正如我們到目前為止所看到的,Taking input from a standard system and giving output to the standard system is always a good idea to improve code efficiency,This is always required for competitive programming.可是等等！Would you like to write these long lines every time you need them？那麼,使用 Python 有什麼好處.
Let's discuss a solution to this problem.What we can do is let us create separate functions to take various types of input,並在需要時調用它們. \
When you want to enter a specific integer integer given in a single line
Suppose the input is of the following form \
5 7 19 20
We want separate variables to refer to them.我們想要的是： \
a = 5
b = 7
c = 19
d = 20
因此,我們可以創建一個名為get_ints() 的函數,如下所示：
import sys
def get_ints(): return map(int, sys.stdin.readline().strip().split())
a,b,c,d = get_ints()
Now you don't have to write this line again and again.您只需調用get_ints() Functions can accept input in this form.在get_ints函數中,我們使用了map 函數.
When you want to enter a list of integers given in a single line
Suppose the input is of the following form\
1 2 3 4 5 6 7 8
We want a single variable to hold the entire list of integers.我們想要的是： \
Arr = [1, 2, 3, 4, 5, 6, 7, 8]
因此,Here we will create a file called get_list() 的函數,如下所示：
import sys
def get_ints(): return list(map(int, sys.stdin.readline().strip().split()))
Arr = get_ints()
Now you don't have to write this line again and again.您只需調用get_ints() Functions can take input in this form\
when you want to enter a string
Suppose the input is of the following form \
juejin is the best platform to practice coding.
And we hope that a single reference variable will hold this string.我們想要的是： \
string = "juejin is the best platform to practice coding."
因此,Here we will create a file called get_string() 的函數,如下所示：
import sys
def get_string(): return sys.stdin.readline().strip()
string = get_string()
Now you don't have to write this line again and again.您只需要調用get_string() function to get the input in this form Add buffer pipes io：(Python 2.7)
1.Just before submitting the code 添加緩沖 IOcode for faster output.
2.io.BytesIOThe nice thing about objects is that they implement a common interface（通常稱為“類文件”對象）.BytesIOObjects have an internal pointer,每次調用 read(n) The pointer will advance.
3.atexitModules provide a simple interface to register functions to be called when the program shuts down gracefully.系統_****Modules also provide a hook sys.exitfunc,But only one function can be registered there.atexit 注冊表Can be used by multiple modules and libraries simultaneously .
# 模板開始
#####################################
# For generic level input/Import library for output processing
import atexit, io, sys
# Stream implementation using in-memory byte buffers. 它繼承了 BufferedIOBase.
buffer = io.BytesIO()
sys.stdout = buffer
# Print via here
@atexit.register
def write():
sys.stdout.write(buffer.getvalue())
#####################################
# 模板結束
# follow the usual approach
# 輸入 N
n = int(input())
# 輸入數組
arr = [int(x) for x in input().split()]
# 初始化變量
summation = 0
# 計算總和
for x in arr:
summation += x
# 打印答案
print(summation)
Usually when dealing with large amounts of data,Normal methods cannot be executed within the time limit.方法 2 Helps maintain a lot I/O 數據.方法 3 是最快的.通常,通過方法 2 和 3 Can help with greater than 2 或 3 MB input data file.
注意： 上述代碼在 Python 2.7 中,用於 Python 3.X 版本.只需將raw_input() 替換為Python 3.X 的 input()語法.Rest should work fine.
