371. Sum of two integers [easy] (Python) __python

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The original title of https://leetcode.com/problems/sum-of-two-integers/

Calculate the sum of two integers a and B, but you are don't allowed to use the operator + and-.

Example:
Given A = 1 and b = 2, return 3. Title Translation

Calculates the and of two integers a and B, but cannot use operator plus and minus signs.
For example: Given a=1,b=2, return 3. method of Thinking

Since you cannot use addition and subtraction, use a bitwise operation. The following example of computational 5+4 illustrates how to add a bitwise operation to an addition:
1. Use binary to express two addends, a=5=0101,b=4=0100;
2. With and (&) operation to get all the bits on the carry carry=0100;
3. Use XOR (^) operation to find A and B different bits, assign value to a,a=0001;
4. Move the carry carry left one position, assign value to b,b=1000;
5. Loop until the carry carry is 0, this time get a=1001, that is, the last sum.

It's a normal idea, but it's a bit of a hassle for python. Because Python's integer is not fixed 32 bits, so need to do some special processing, see the code specifically.
The code takes a number to 0x100000000 (note: Python's modulo operation results in a non-negative number, which is the hope that the binary representation of the numbers from the 32nd bit to the higher bit is 0 (the lowest bit is the No. 0) to simulate a 32-bit int on the 0-31-bit. idea of a

Iterative solution.

Code

Class Solution (object):
    def getsum (self, A, b): ""
        : Type a:int
        : Type b:int
        : Rtype:int
        ""  C6/>while b!= 0:
            carry = A & B
            a = (a ^ b)% 0x100000000
            B = (carry << 1)% 0x100000000
        return A If a <= 0x7fffffff else a | (~0x100000000+1)

Idea two

Recursive solution.

Code

Class Solution (object):
    def getsum (self, A, b): ""
        : Type a:int
        : Type b:int
        : Rtype:int "" "
        tmp_a = Self.add (A, b) return
        tmp_a if tmp_a <= 0x7fffffff Else tmp_a | (~0x100000000+1)

    def add (self, A, b): Return
        a If B = 0 Else Self.add ((a ^ b)% 0x100000000, ((A & B) << 1)% 0x100000000)

PS: Novice Brush Leetcode, new handwritten blog, write wrong or write is not clear also please help point out, thank you.
Reprint Please note: http://blog.csdn.net/coder_orz/article/details/52034541