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# Time: +: O(d * t), t is the number of terms,
# d is the average degree of terms
# -: O(d * t)
# *: O(d * t^2)
# eval: O(d * t)
# to_list: O(d * tlogt)
# Space: O(e + d * t), e is the number of evalvars
import collections
import itertools
class Poly(collections.Counter):
def __init__(self, expr=None):
if expr is None:
return
if expr.isdigit():
self.update({(): int(expr)})
else:
self[(expr,)] += 1
def __add__(self, other):
self.update(other)
return self
def __sub__(self, other):
self.update({k: -v for k, v in other.items()})
return self
def __mul__(self, other):
def merge(k1, k2):
result = []
i, j = 0, 0
while i != len(k1) or j != len(k2):
if j == len(k2):
result.append(k1[i])
i += 1
elif i == len(k1):
result.append(k2[j])
j += 1
elif k1[i] < k2[j]:
result.append(k1[i])
i += 1
else:
result.append(k2[j])
j += 1
return result
result = Poly()
for k1, v1 in self.items():
for k2, v2 in other.items():
result.update({tuple(merge(k1, k2)): v1*v2})
return result
def eval(self, lookup):
result = Poly()
for polies, c in self.items():
key = []
for var in polies:
if var in lookup:
c *= lookup[var]
else:
key.append(var)
result[tuple(key)] += c
return result
def to_list(self):
return ["*".join((str(v),) + k)
for k, v in sorted(self.items(),
key=lambda x: (-len(x[0]), x[0]))
if v]
class Solution(object):
def basicCalculatorIV(self, expression, evalvars, evalints):
"""
:type expression: str
:type evalvars: List[str]
:type evalints: List[int]
:rtype: List[str]
"""
def compute(operands, operators):
left, right = operands.pop(), operands.pop()
op = operators.pop()
if op == '+':
operands.append(left + right)
elif op == '-':
operands.append(left - right)
elif op == '*':
operands.append(left * right)
def parse(s):
if not s:
return Poly()
operands, operators = [], []
operand = ""
for i in reversed(xrange(len(s))):
if s[i].isalnum():
operand += s[i]
if i == 0 or not s[i-1].isalnum():
operands.append(Poly(operand[::-1]))
operand = ""
elif s[i] == ')' or s[i] == '*':
operators.append(s[i])
elif s[i] == '+' or s[i] == '-':
while operators and operators[-1] == '*':
compute(operands, operators)
operators.append(s[i])
elif s[i] == '(':
while operators[-1] != ')':
compute(operands, operators)
operators.pop()
while operators:
compute(operands, operators)
return operands[-1]
lookup = dict(itertools.izip(evalvars, evalints))
return parse(expression).eval(lookup).to_list()
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