Divide Two Integers

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

解答：

public int divide(int dividend, int divisor) {
		boolean negative = (dividend<0 && divisor>0) ||
				(dividend>0 && divisor<0);
		
		int result = 0;
		long div_dividend = Math.abs((long)dividend);
		//Math.abs(-2147483648)的结果为-2147483648，这是因为溢出的原因，因此这里一定先要做类型转换才行
		long div_divisor = Math.abs((long)divisor);		
		
		while(div_dividend >= div_divisor) {
			int shift = 0;
			while( (div_divisor<<shift) <= div_dividend ) {
				++shift;
			}
			--shift;
			result += (1<<shift);
			div_dividend -= (div_divisor<<shift);
		}
		
		return negative? -result : result;
    }

这道题一定要注意整数溢出的问题