Personal Leetcode solution(Python)

class Solution(object):
    def singleNumber(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        result = 0
        for each in range(len(nums)):
            result ^= nums[each]
        return result

class Solution(object):
    def reverseString(self, s):
        lst = []
        for i in range(len(s)):
            lst.append(s[-(i + 1)])
        lst = ‘‘.join(lst)
        return lst

class Solution(object):
    def canWinNim(self, n):
        val = n % 4
        if val != 0:
            return True
        else:
            return False

class Solution(object):
    def countBits(self, num):
        val = [0]
        while len(val) <= num:
            val += [i + 1 for i in val]
        return val[:num + 1]

class Solution(object):
    def half_adder(self, a, b):
        s = a ^ b
        cin = a & b
        return s, cin

    def full_adder(self, a, b, cin):
        s1, c1 = self.half_adder(a, b)
        s2, c2 = self.half_adder(cin, s1)
        c_out = c1 | c2
        return s2, c_out

    def getSum(self, a, b):
        mask = 1
        ci = 0
        sum_total = 0

        while mask <= 0x080000000:
            a1 = a & mask
            b1 = b & mask
            (s, ci) = self.full_adder(a1, b1, ci)
            sum_total = sum_total | s
            ci <<= 1
            mask <<= 1
            print "s: " + str(s) + "     ci: " + str(ci)
        maximum = 0x7FFFFFFF
        mask = 0xFFFFFFFF

        if sum_total > maximum:
            sum_total = ~(sum_total ^ mask)

        return sum_total