LeetCode OJ：Divide Two Integers（两数相除）

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

If it is overflow, return MAX_INT.

两数相除，不能用*,/,% 那么只能用位移运算了，注意边界条件防止溢出，代码如下：

 1 class Solution {
 2 public:
 3     int divide(int dividend, int divisor) {
 4         int sign1 = dividend > 0 ? 1 : -1;
 5         int sign2 = divisor > 0 ? 1 : -1;
 6         long long d1 = abs(static_cast<long long>(dividend));
 7         long long d2 = abs(static_cast<long long>(divisor));
 8         int res = 0;
 9         while(d1 >= d2){
10             long long tmp = d2;
11             for(int i = 0; d1 >= tmp; ++i){
12                 d1 -= tmp;
13                 tmp <<= 1;
14                 res += 1LL << i;
15             }
16         }
17         if(sign1 == sign2){
18             if(res == INT_MIN)
19                 return INT_MAX;
20             return res;
21         }else
22             return res * -1;
23     }
24 };

PS:这题溢出情况相当恶心。