uva solution Throwing cards away II-10940

Hints:using dynamic programming
Provlen link
solution:
#include<cstdio>
#include<iostream>
using namespace std;
int main()
{
    int i,n,next,cards[500000+1];
    cards[1]=1;
    cards[2]=2;
    next=2;
    for(i=3;i<=500000;i++)
    {
        if(i<next) next=2; cards[i]=next;
        next+=2;
    }
    while(cin>>n)
    {
        if(n==0) break;
        else cout<<cards[n]<<endl;
    }
    return 0;

}