python 內部自帶大整數運算能力,整數運算不會溢出,只要內存足夠,就oK
下面的例子演示了兩個32位整數加法的情況(通過位運算實現),爲了模擬溢出的效果,必須人工的進行位運算,~運算符除了求反,還是二進制的補運算符,運算過後的二進制數字按照補碼解釋,例如 ~(0011 1100) = (1100 0011) = -61
def getSum(a, b):
"""
:type a: int
:type b: int
:rtype: int
"""
MAX = 0X7fffffff
MIN = 0X80000000
while b != 0 :
a,b = a^b,(a&b)<<1
print(" a = {0:b},b = {1:b}".format(a,b))
return a
def getSum_(a, b):
"""
:type a: int
:type b: int
:rtype: int
"""
MAX = 0x7FFFFFFF
MIN = 0x80000000
mask = 0xFFFFFFFF
while b != 0:
a, b = (a ^ b) & mask, ((a & b) << 1) & mask
print(type(a))
print(" a = {0:b},b = {1:b}".format(a,b))
return a if a <= MAX else ~(a^mask)
print(getSum_(-1,-1))
print(getSum(-1,1))