給定兩個二進制字符串，返回他們的和（用二進制表示）。

輸入為非空字符串且只包含數字 1 和 0。

示例 1:

輸入: a = "11", b = "1"
輸出: "100"

示例 2:

輸入: a = "1010", b = "1011"
輸出: "10101"

class Solution:
    def addBinary(self, a, b):
        """
        :type a: str
        :type b: str
        :rtype: str
        """
        a_len=len(a)
        b_len=len(b)
        result
 
=‘‘
        next =‘0‘
        while a_len and b_len :
            if sum([int(next),int(a[a_len-1]),int(b[b_len-1])]) == 3:
                result +=‘1‘
                next = ‘1‘
            elif sum([int(next),int(a[a_len-1]),int(b[b_len-1])]) == 2:
                result+=‘0‘
                next =‘
 
1‘
            elif sum([int(next),int(a[a_len-1]),int(b[b_len-1])]) == 0:
                result+=‘0‘
                next =‘0‘
            elif sum([int(next),int(a[a_len-1]),int(b[b_len-1])]) < 2:
                result+=‘1‘
                next =‘0‘
            a_len-=1
            b_len-=1
        new 
 
= a[:a_len] if a_len > b_len else b[:b_len]
        if new:
            for i in new[::-1]:
                if sum([int(next),int(i)]) == 2:
                    result+=‘0‘
                    next =‘1‘
                elif sum([int(next),int(i)]) == 1:
                    result+=‘1‘
                    next =‘0‘
                else:
                    result+=‘0‘
                    next =‘0‘
        if next != 0:
            result+=next
        return (result[::-1])

class Solution:
    def addBinary(self, a, b):
        """
        :type a: str
        :type b: str
        :rtype: str
        """

        return format(int(a,2)+int(b,2),"b")

【leetcode 簡單】第十六題 二進制求和