24点计算器Python脚本

使用Python脚本枚举24点答案，去除冗余括号，效率没有Ruby版本的好，可能因精度的关系，和其它人些的答案数目不一致，记录之。

# -*- coding:gbk -*-

import itertools as itt
import re

nums = [7, 6, 4, 8]
ops = ['+', '-', '*', '/']
levels = [0, 1, 2]

def simplest(exprstr):
	patterns = [re.compile(r"\((\(.+)\)(.+)")\
		,re.compile(r"\((.+\))\)(.+)")\
		,re.compile(r"(.+)\((\(.+)\)")\
		,re.compile(r"(.+)\((.+\))\)")\
		,re.compile(r"(.+)\(([^\)]+)\)(.+)")\
		,re.compile(r"\((.+)\)(.+\(.+\))")\
		,re.compile(r"(\(.+\).+)\((.+)\)")]
	rl = [exprstr,exprstr.replace("(","").replace(")","")]
	for p in patterns:
		m = p.match(exprstr)
		if m is not None:
			rl.append("".join(m.groups()))
	rl.sort(key = len)	
	for r in rl:
		if abs(eval(r) - 24.0) < 1e-10:
			return r

def fmtexpr(operand, operators, priority):
	i = [i for i, x in enumerate(priority) if x == max(priority)].pop(0)
	operand[i] = "({}{}{})".format(operand[i],operators.pop(i),operand.pop(i + 1))
	priority.pop(i)
	return operand.pop(0) if len(priority) == 0 else fmtexpr(operand,operators,priority)

def check24p(num, op, level):
	numfloat = [float(n) for n in num]
	return fmtexpr(numfloat, op, level)

answer = set([])

ai = 0
for num in itt.permutations(nums, r = 4):
	for op in itt.product(ops, repeat = 3):
		for level in itt.permutations(levels, r = len(levels)):
			exprstr = check24p(list(num), list(op), list(level))
			try:
				if abs(eval(exprstr) - 24.0) < 1e-10:
					ai = ai + 1
					exprstr = simplest(exprstr[1:-1])
					answer.add(exprstr.replace(".0",""))
			except ZeroDivisionError:
				continue

print("共{}种解法，化简后剩余{}种解法：".format(ai, len(answer)))
for a in answer:
	print("我答24点 " + a)