LeetCode: Divide Two Integers [028]

class Solution {
public:
    int divide(int dividend, int divisor) {
        if(divisor==0 || dividend==0)return 0;
        if(divisor==1)return dividend;
        if(divisor==-1)return 0-dividend;
        
        bool isNegative=false;
        if((dividend<0&&divisor>0)||(dividend>0&&divisor<0))isNegative=true; //判断正负
        long long dend=dividend;
        long long dsor=divisor;
        long long totalSum=0;       //为了防止越界情况的发生，使用long long类型
        long long sum=0;
        int totalCount=0;
        int count=0;
        if(dend<0)dend=abs(dend);   //取正
        if(dsor<0)dsor=abs(dsor);
        while(sum+dsor<=dend-totalSum){
            count=1;
            sum=dsor;
            while(sum+sum<=dend-totalSum){
                sum+=sum;
                count+=count;
            }
            totalSum+=sum;
            totalCount+=count;
            sum=0;
            count=0;
        }
        if(isNegative)return 0-totalCount;
        else return totalCount;
        
    }
};