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[LeetCode] 29. Divide Two Integers

2017-04-01 01:21  amadis  阅读(143)  评论(0)  编辑  收藏  举报

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

If it is overflow, return MAX_INT.

 

 1 class Solution {
 2 public:
 3     int divide(int dividend, int divisor) {
 4         if (!divisor) return (dividend >= 0 ? INT_MAX : INT_MIN);
 5         if ((dividend == INT_MIN) && (divisor == -1)) return INT_MAX;
 6         
 7         bool isNeg = false;
 8         if (((dividend > 0) && (divisor < 0)) || ((dividend < 0) && (divisor > 0))){
 9             isNeg = true;
10         }
11         
12         unsigned long long dvd = abs((long long)(dividend));
13         unsigned long long dvs = abs((long long)(divisor));
14         unsigned long long dvs_orig = dvs;
15         
16         int res = 0;
17         int i = 0;
18         
19         while (dvd >= (dvs << i)) i++;
20         
21         while (dvd >= dvs_orig){
22             if (dvd >= dvs << i){
23                 dvd -= dvs << i;
24                 res += 1 << i;
25             }
26             i--;
27         }
28         
29         return (isNeg ? (0 - res) : (res));        
30     }
31 };