ZhouYang1993

class MyClass(object):
  data = 0

  def __init__(self, value):
    self.instance_data = value
        
MyClass.data
# 0
my_instance = MyClass(3)
my_instance.data

ZhouYang1993

class MyClass(object):
    data = []
 
    def __init__(self, value):
      self.instance_data = value
         
my_instance = MyClass(3)
my_instance.data
# []

ZhouYang1993

try:
    f = open('test_file.txt', 'r')
    # do some operations
finally:
    if f:
        f.close()

ZhouYang1993

try:
    f = open('test_file.txt', 'r')
    print(f.read())
finally:
    if f:
        f.close()

ZhouYang1993

with open('test_file.txt', 'r') as f:
    print(f.read())

ZhouYang1993

import bisect

with open('ip1.txt', 'r') as f1:
    list1 = [line.rstrip('\n') for line in f1.readlines()]
with open('ip2.txt', 'r') as f2:
    list2 = [line.rstrip('\n') for line in f2.readlines()]

list2.sort()
same_ip = []
for i in list1:

ZhouYang1993

with open('test.txt', 'w') as f:
    f.write('Hello, world!')

ZhouYang1993

# Example 1
with open('test1.txt', 'w') as f:
    f.writelines(["1", "2", "3"])
# The contents of test1.txt is:
# 123

# Example 2
with open('test2.txt', 'w') as f:
    f.writelines(["1\n", "2\n", "3\n"])
#    The contents of test2.txt is:

ZhouYang1993

# The contents in test.txt are:
# Hello,Yang!
with open('test.txt', 'r+') as f:
    print(f.read())
    f.seek(6, 0)
    print(f.read())

# Hello,Yang!
# Yang!

ZhouYang1993

class Solution:
    def isValid(self, s: str) -> bool:
        mapping = {')': '(', ']': '[', '}': '{'}
        stack = []
        for char in s:
            if mapping.get(char):
                if not stack:
                    return False
                else:
                    if stack[-1] == mapping[char]: