29. Divide Two Integers 

 1 class Solution {
 2     public int divide(int dividend, int divisor) {
 3         long count = 0;
 4         if(dividend == 0) return 0;
 5         //divisor和dividend都要变成正数和long再进行处理
 6         if((dividend > 0 && divisor >0) || (dividend < 0 && divisor < 0)) {
 7              long ldivisor = Math.abs((long)divisor);
 8              long ldividend = Math.abs((long)dividend);
 9              count = longdivide(ldividend, ldivisor);
10             
11         }else {
12             long ldivisor = Math.abs((long)divisor);
13             long ldividend = Math.abs((long)dividend);
14             count = -longdivide(ldividend, ldivisor);
15             }
16             
17         //overflow处理
18         if(count > 0) {
19             return (int) (count > Integer.MAX_VALUE ? Integer.MAX_VALUE : count);
20         }else {
21             return (int) (count < Integer.MIN_VALUE ? Integer.MIN_VALUE : count);
22         }
23         
24         
25     }
26     
27     //类似binary search
28     public long longdivide(long dividend, long divisor) {
29         if(dividend < divisor) return 0;
30         long multiple = 1;
31         long sum = divisor;
32         while((sum + sum) < dividend) {
33             sum += sum;
34             multiple +=multiple;
35         }
36         return multiple + longdivide(dividend - sum, divisor);
37         
38     }
39 }

 

posted @ 2018-09-08 05:34  jasoncool1  阅读(120)  评论(0)    收藏  举报