LeetCode开心刷题十六天——29. Divide Two Integers*

#include<algorithm>
#include <iostream>
#include <map>
#include <queue>
#include <vector>

using namespace std;

class Solution
{
public:
    int divide(int divided,int divisor)
    {
        long long m=abs((long long)divided),n=abs((long long)divisor);
        //cout<<m<<" "<<n<<endl;
        long long res=0,p=1,t=n;
        if(m<n) return 0;
        while(m>(t<<1))
        {
            t<<=1;
            p<<=1;
        }
        res+=p+divide(m-t,n);
        //cout<<"res"<<res<<endl;
        if((divided>0)^(divisor>0)) res=-res;
        //at first,I only write following sentence
        return (res>INT_MAX)?INT_MAX:res;

    }
};

int main()
{
   int a,b,res;
   cin>>a>>b;
   Solution s;
   res=s.divide(a,b);
    cout<<res<<endl;
    return 0;
}

1.First thing is clarify each step;

whether the current function has a return value;if it has which variable should we use to get this value?

My fault is put this directly.this need a variable=?:

(res>INT_MAX)?INT_MAX:res;

2.Really understand what substitution mean,I use m,n to replace divide divisor during operational process
make it abs and long long.But when you write a code ,when you feel you need one to replace then i define one,
but if we directly see the answer,The bad thing is we directly see the replace variable even before we understand
why we need this ,if we cannot make it clear,things like recursion can go wrong.
PS:this following sentence meets my requirements perfectly.xor opperation >><< operation ,they are not commonly
used but they can greatly simplify calculations.

if((divided>0)^(divisor>0)) res=-res;