poj 2033 Alphacode

#include<iostream>
#include<string>
using namespace std;
int arr[10000],len,ans[10000];
int dp(int id)
{
    if(ans[id]!=-1)
        return ans[id];
    int s;
    if(id==len)
        s=1;
    else if(id==len-1)
        s=arr[id]>0?1:0;
    else if(arr[id]==0)
        s=0;
    else if(10*arr[id]+arr[id+1]<=26)
            s=dp(id+1)+dp(id+2);
    else 
        s=dp(id+1);
    ans[id]=s;
    return ans[id];
}
int main()
{
    string str;
    while(cin>>str&&str!="0")
    {
        len=str.size();
        for(int i=0;i<len;++i)
            arr[i]=str[i]-'0';
        memset(ans,-1,sizeof(ans[0])*(len+1));
        cout<<dp(0)<<endl;
    }
    return 0;
}