Divide Two Integers leetcode java

題目：

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

 

題解：

這道題我自己沒想出來。。。乘除取模都不讓用。。那只有加減了。。。我參考的http://blog.csdn.net/perfect8886/article/details/23040143

 

代碼如下：

 

 
           1       
          public  
          int divide( 
          int dividend,  
          int divisor) {   
          
 
           2          
          if (dividend == 0 || divisor == 0) {   
          
 
           3              
          return 0;   
          
 
           4         }   
          
 
           5          
          boolean isNeg = (dividend > 0 && divisor < 0)   
          
 
           6                 || (dividend < 0 && divisor > 0);   
          
 
           7          
          long a = Math.abs(( 
          long) dividend);   
          
 
           8          
          long b = Math.abs(( 
          long) divisor);   
          
 
           9          
          if (b > a) {   
          
 
          10              
          return 0;   
          
 
          11         }   
          
 
          12    
          
 
          13          
          long sum = 0;   
          
 
          14          
          long pow = 0;   
          
 
          15          
          int result = 0;   
          
 
          16          
          while (a >= b) {   
          
 
          17             pow = 1;   
          
 
          18             sum = b;   
          
 
          19              
          while (sum + sum <= a) {   
          
 
          20                 sum += sum;   
          
 
          21                 pow += pow;   
          
 
          22             }   
          
 
          23             a -= sum;   
          
 
          24             result += pow;   
          
 
          25         }   
          
 
          26          
          return isNeg ? -result : result;   
          
 
          27     }  
         

Reference：

 http://blog.csdn.net/perfect8886/article/details/23040143