sicily 1298. 数制转换

#include<iostream>
using namespace std;
int res[1000];
int main()
{
    int n;
    while(cin>>n)
    {
        if(n==0)
        {
            cout<<"0\n";
            continue;
        }
        int m,r=0;
        while(n!=0)
        {
            if(n>0)
            {
                if(n%3!=2)
                {
                    res[r++]=n%3;
                    n/=3;
                }
                else    //比如n=5, 应该将n看作是 3*2+(-1) 
                {
                    res[r++]=-1;
                    n=n/3+1;
                }
            }
            else
            {
                m=-n;
                if(m%3==0)
                {
                    res[r++]=0;
                    n/=3;
                }
                else if(m%3==1)        //比如 n=-4,看作是 -4=3*-1+(-1)
                {
                    res[r++]=-1;
                    n/=3;
                }
                else                //比如 n=-5,看作是 -5=3*-2+(1)
                {
                    res[r++]=1;
                    n=n/3-1;
                }
            }
        }
        for(int i=r-1;i>=0;--i)
            if(res[i]==-1)
                cout<<"-";
            else
                cout<<res[i];
        cout<<endl;
    }
    return 0;
}