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;
}
/*

*/