[Leetcode] Divide Two Integers (Java)

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

输入两个整数，dividend, divisor，不要使用乘法，除法，取模运算，求出a/b的值。

如果每次减divisor，会超时，让sum=b，每次sum翻倍，然后count也翻倍，效率会高点儿

public class DivideTwoIntegers {
public int divide(int dividend, int divisor) {
int res=0;
if(dividend==0||divisor==0)
return 0;
boolean flag = true;
if((dividend>0&&divisor<0)||(dividend<0&&divisor>0))
flag = false;
long a = Math.abs((long)dividend);
long b = Math.abs((long)divisor);
long sum;
int count;
while(a>=b){
sum = b;
count = 1;
while(sum+sum<=a){
count+=count;
sum+=sum;
}
a-=sum;
res+=count;
}
return flag?res:-res;
}
public static void main(String[] args) {
int dividend = 1;
int divisor = 1;
System.out.println(new DivideTwoIntegers().divide(dividend, divisor));
}
}