LeetCode: Divide Two Integers

很多bug还不清楚。。用了网上答案

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;
    }
};