HDU 4814 Golden Radio Base

#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<=b;++i)
#define ms(arr,a) memset(arr,a,sizeof arr)
int pos[55],neg[75];
int& a(int i)
{
    if(i<0)return neg[-i];
    else return pos[i];
}
int main()
{
    int n;
    while(~scanf("%d",&n))
    {
        ms(pos,0);
        ms(neg,0);
        a(0)=n;
        bool bad=true;
        int pos_max=0,neg_max=0;
        while(bad)
        {
            bad=false;
            for(int i=neg_max;i<=pos_max;i++)
            {
                if(a(i)>1)
                {
                    a(i+1)=a(i+1)+a(i)/2;
                    a(i-2)=a(i-2)+a(i)/2;
                    a(i)%=2;
                    if(i+1>pos_max)pos_max=i+1;
                    if(i-2<neg_max)neg_max=i-2;
                    bad=true;
                }
            }
            for(int i=neg_max;i<=pos_max;i++)
            {
                if(a(i)&&a(i+1))
                {
                    int tmp=min(a(i),a(i+1));
                    a(i+2)+=tmp;
                    a(i)-=tmp,a(i+1)-=tmp;
                    if(i+2>pos_max)pos_max=i+2;
                    bad=true;
                }
            }
            while(a(neg_max)==0&&neg_max<=0)neg_max++;
        }
        for(int i=pos_max;i>=0;i--)
        {
            printf("%d",a(i));
        }
        if(neg_max<0)
        {
            printf(".");
            for(int i=-1;i>=neg_max;i--)printf("%d",a(i));
        }
        printf("
");
    }
}