leetcode-29 Divide Two Integers

问题描述：

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

If it is overflow, return MAX_INT.

 

问题分析：

转化为位运算与加减法相结合；

注意处理Integer.MIN_VALUE (-2147483648)的特殊情况，此时应当返回Integer.MAX_VALUE(2147483647)

代码：

public class Solution {
public int divide(int dividend, int divisor) {
// 处理特殊情况
if(divisor == 1)
return dividend;
if(dividend == Integer.MIN_VALUE && Math.abs(divisor)== 1)
return Integer.MAX_VALUE;
// 判断结果的符号
int sign = (dividend > 0 ^ divisor > 0) ?-1 : 1;

long ans = 0;
long end = Math.abs((long)dividend);
long sor = Math.abs((long)divisor);

// 实现除法的核心
while(end >= sor) {
long temp = sor;
long power = 1;
while((temp << 1) < end) {
power <<= 1;
temp <<= 1;
}
ans += power;
end -= temp;
}
return (int)(sign * ans);
}
}