LeetCode_Divide Two Integers

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

int divide(int dividend, int divisor) {
int flag =1;
if(dividend <0) flag *= -1;
if(divisor <0)  flag *= -1;
unsigned long long d1 = abs((long long)dividend);
unsigned long long d2 = abs((long long)divisor);
unsigned long long temp;

if(d1 < d2)  return 0;
if(d1 == d2) return 1* flag;
if(d2 == 1)  return d1* flag;

unsigned long long count = 1;
temp = d2;
while(d1>temp){
temp = temp<<1 ;
count = count<<1 ;
}

int result = 0;
while(d1 > d2){
//下面判断中的=很关键
while(d1 >= temp){
d1 = d1 - temp;
result +=  count;
}
temp = temp >>1;
count = count >>1;

}
return result*flag;
}

这里解释下为什么必须要使用long long 才能A掉，因为计算机中的数字用补码表示，所以负数能够表示的范围比较大，去符号变正数后超过int的表示范围，所以必须使用long long