其实原来是微信推送的东西，第五题比较感兴趣
问题5
编写一个在1，2，…，9（顺序不能变）数字之间插入+或-或什么都不插入，使得计算结果总是100的程序，并输出所有的可能性。例如：1 + 2 + 34 – 5 + 67 – 8 + 9 = 100。
Ps：如果你不知道的话，点击这里，阅读我的解决方案。
CODES = ['+', '-', '']
NUMBERS = [1, 2, 3, 4, 5, 6, 7, 8, 9]
def list_calculate(num):
if num == 1:
return [[code] for code in CODES]
else:
return [[code] + code_list for code in CODES for code_list in list_calculate(num - 1)]
def calculate_equation(equation):
result, temp_number, temp_code = 0, NUMBERS[0], '+'
for i in range(len(equation)):
the_number = NUMBERS[i + 1]
if equation[i] is '+' or equation[i] is '-':
if temp_code is '+':
result += temp_number
elif temp_code is '-':
result -= temp_number
elif temp_code is None:
result = the_number
temp_number, temp_code = the_number, equation[i]
else:
temp_number = temp_number * 10 + the_number
if temp_code is '+':
result += temp_number
elif temp_code is '-':
result -= temp_number
elif temp_code is '':
result = result * 10 + temp_number
return result
def print_equation(equation):
result = '%s' % NUMBERS[0]
for i in range(len(equation)):
if not equation[i] is '':
result += ' %s ' % equation[i]
result += '%s' % NUMBERS[i + 1]
result += ' = %s' % calculate_equation(equation)
print result
equations = list_calculate(len(NUMBERS) - 1)
for equation in equations:
if calculate_equation(equation) == 100:
print_equation(equation)
我现在在想除了穷举还有啥好办法，比如根据位数大致算出一个范围什么的