def build_parse_tree(exp: str):
_exp_list = exp.split()
_stack = Stack()
_tree = BinaryTree('')
_stack.push(_tree)
_current = _tree
for _item in _exp_list:
if _item == '(':
_current.insert_left('')
_stack.push(_current)
_current = _current.get_left_child()
elif _item in ['+', '-', '*', '/']:
# set current node value
_current.set_root_val(_item)
_current.insert_right('')
_stack.push(_current)
_current = _current.get_right_child()
# number
elif _item not in ['+', '-', '*', '/', ')']:
_current.set_root_val(int(_item))
_current = _stack.pop()
elif _item == ')':
_current = _stack.pop()
else:
raise ValueError
return _tree
def int2str_by_stack(num: int, base: int):
_stack = Stack()
_ref = '0123456789ABCDEF'
while num > 0:
if num < base:
_stack.push(_ref[num])
else:
_stack.push(_ref[num % base])
num //= base
_ret = ''
while not _stack.is_empty():
_ret += str(_stack.pop())
return _ret
def postfix_math(s: str):
_stack = Stack()
_srclst = s.split()
_refer = string.digits
for _item in _srclst:
if _item in _refer:
_stack.push(int(_item))
else:
_op1 = int(_stack.pop())
_op2 = int(_stack.pop())
# op2 operator op1
_value = calc(_item, _op2, _op1)
_stack.push(_value)
return _stack.pop()
def check_par_brackets(s):
_stack = Stack()
_ok = True
_index = 0
while _index < len(s) and _ok:
_item = s[_index]
if _item == '(':
_stack.push(_item)
else:
if _stack.is_empty():
_ok = False
return _ok
else:
_stack.pop()
_index += 1
# _stack must be empty
return _ok and _stack.is_empty()
def devide_by2(decimal):
_remstack = Stack()
while decimal > 0:
_rem = decimal % 2
_remstack.push(_rem)
decimal //= 2
_ret = ''
while not _remstack.is_empty():
_ret += str(_remstack.pop())
return _ret
def devide_by_base(decimal, base):
_digits = '0123456789ABCDEF'
_remstack = Stack()
while decimal > 0:
_rem = decimal % base
_remstack.push(_rem)
decimal //= base
_ret = ''
while not _remstack.is_empty():
_ret += str(_digits[_remstack.pop()])
return _ret
def check_brackets(s):
_stack = Stack()
_ok = True
_index = 0
while _index < len(s) and _ok:
if s[_index] in '([{':
_stack.push(s[_index])
else:
if _stack.is_empty():
_ok = False
return _ok
else:
_open = _stack.pop()
# s[_index] is close symbol
if not matches(_open, s[_index]):
_ok = False
return _ok
_index += 1
return _ok and _stack.is_empty()
def infix2prefix(s: str):
_priority = {
'*': 3,
'/': 3,
'+': 2,
'-': 2,
'(': 1,
}
_ret = []
_opstack = Stack()
_srclst = s.split()
_refer = string.ascii_uppercase + string.digits
_index = 0
while _index < len(_srclst):
_item = _srclst[_index]
if _item == '(':
_opstack.push(_item)
elif _item in _refer:
_ret.append(_item)
elif _item == ')':
_top = _opstack.pop()
# maybe exist multi operations rather than one.
# so need to add continually until meet '('
while _top != '(':
_ret.append(_top)
_top = _opstack.pop()
else:
while (not _opstack.is_empty()
) and _priority[_opstack.peek()] >= _priority[_item]:
_ret.append(_opstack.pop())
_opstack.push(_item)
_index += 1
while not _opstack.is_empty():
_ret.append(_opstack.pop())
return ''.join(_ret)
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 6/14/18 11:17 AM
# @Author : Miracle Young
# @File : app.py
from python_data_structure.base_data_structure.stack import Stack
_stack = Stack()
print(_stack.is_empty())
_stack.push(4)
_stack.push('dog')
print(_stack.peek())
_stack.push(True)
print(_stack.size())
print(_stack.is_empty())
_stack.push(8.4)
print(_stack.pop())
print(_stack.pop())
print(_stack.size())
from python_data_structure.base_data_structure.queue import Queue
_q = Queue()
print(_q.is_empty())
print(_q.enqueue(1))
print(_q.enqueue(10))
print(_q.dequeue())
print(_q.size())