Lintcode：A + B 问题

+

32位

a=1

b=2

3

class Solution:
"""
@param: a: An integer
@param: b: An integer
@return: The sum of a and b
"""
def aplusb(self, a, b):
# write your code here
sum = 0
carry = 0
for i in range(32):
a1 = a & 1
b1 = b & 1
val = 0
if a1== 0 and b1 ==0 and carry ==0:
val =0
carry = 0
elif a1 == 1 and b1 == 1 and carry ==1:
val =1
carry =1
elif a1 == 0 and b1 ==0 or a1==0 and carry ==0 or b1 ==0 and carry ==0:
val = 1
carry = 0
else:
val = 0
carry = 1
val = val << i
sum = sum|val
a = a>>1
b = b>>1
return sum

class Solution {
public:
/*
* @param : An integer
* @param : An integer
* @return: The sum of a and b
*/
int aplusb(int a, int b) {
// write your code here
if(a==0)
return b;
if(b==0)
return a;
int x1 = a ^ b;
int x2 = (a & b) << 1;
return aplusb(x1, x2);
}
};