LeetCode - 29. Divide Two Integers

 29. Divide Two Integers#

Problem's Link
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Mean: 

不使用乘法、除法、取模运算，实现两个数相除.

analyse:

使用移位运算.

Time complexity: O(N)

 

view code

/**
* -----------------------------------------------------------------
* Copyright (c) 2016 crazyacking.All rights reserved.
* -----------------------------------------------------------------
*       Author: crazyacking
*       Date  : 2016-02-19-17.45
*/
#include <queue>
#include <cstdio>
#include <set>
#include <string>
#include <stack>
#include <cmath>
#include <climits>
#include <map>
#include <cstdlib>
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
using namespace std;
typedef long long(LL);
typedef unsigned long long(ULL);
const double eps(1e-8);

class Solution
{
public:
   int divide(int dividend, int divisor)
   {
       if(!divisor || (dividend==INT_MIN && divisor==-1))
           return INT_MAX;
       bool sign=(dividend<0)^(divisor<0);
       long long dvd=labs(dividend);
       long long dvs=labs(divisor);
       int res=0;
       while(dvd>=dvs)
       {
           long long tmp=dvs,multiple=1;
           while(dvd>=(tmp<<1))
           {
               tmp<<=1;
               multiple<<=1;
           }
           dvd-=tmp;
           res+=multiple;
       }
       return sign?-res:res;
   }
};

int main()
{
   Solution solution;
   int a,b;
   while(cin>>a>>b)
   {
       cout<<solution.divide(a,b)<<endl;
   }
   return 0;
}
/*

*/