LeetCode: Divide Two Integers

class Solution {
public:
int divide(int dividend, int divisor) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
bool isnegtive = false;
int multiply = 0;
long long a = dividend;
long long b = divisor;
if (a < 0) {
a = -a;
isnegtive = !isnegtive;
}
if (b < 0) {
b = -b;
isnegtive = !isnegtive;
}
while (b << multiply <= a) {
multiply++;
}
int ret = 0;
for (int i = multiply-1; i >= 0; i--) {
if (b << i <= a) {
ret = ret | (1 << i);
a -= b << i;
}
}
if (isnegtive) ret = -ret;
return ret;
}
};