leetcode[29]Divide Two Integers

Divide two integers without using multiplication, division and mod operator.

If it is overflow, return MAX_INT.

class Solution {

public:

    int divide(int dividend, int divisor) {

    if (dividend==0||divisor==0)return 0;

    int flag=1;

    if ((dividend<0&&divisor>0)||(dividend>0&&divisor<0))

        flag=0;

    if(dividend==divisor)return 1;

    long long a=dividend;

    long long b=divisor;

    a=abs(a);

    b=abs(b);

    if(a<b)return 0;

    long long b0=b;

    int res=0;

    int icount=0;

    int f=1;

    while (f)

    {

        while (a>=b)

        {

            b<<=1;

            icount++;

        }

        icount--;

        b>>=1;

        a-=b;

        res+=(1<<icount);

        if(a<b0)f=0;

        else

        {

            while(a<b)

            {

                b>>=1;

                icount--;

            }

        }

    }

    return flag?res:-res;

    }

};