字典树 板子

#include<bits/stdc++.h>
using namespace std;
struct node
{
    int r;
    node *next[26];
    node()
    {
        r=0;
        memset(next,0,sizeof(next));
    }
};
node root;
int build_trie(string ss)
{
    node *p=&root;
    int flag=0;
    for(int i=0;i<ss.size();i++)
    {
        if( (*p).next[ss[i]-‘0‘]==NULL)
        {
            (*p).next[ss[i]-‘0‘]=new node;
        }
        if( (*p).r==1) flag=1;
        p=(*p).next[ss[i]-‘0‘];
    }
    (*p).r=1;
    if(flag==1) return 1;
    else        return 0;
}

int main()
{
    int temp=0;
    int flag=0;
    string ss;
    while(cin>>ss)
    {
        if(ss=="9")
        {
            temp++;
            if(flag) cout<<"Set "<<temp<<" is not immediately decodable"<<endl;
            else     cout<<"Set "<<temp<<" is immediately decodable"<<endl;
            flag=0;
            for(int i=0;i<=25;i++) root.next[i]=NULL;// zhi zheng qin kong
        }
        else
        {
            if(flag==1) continue;
            if(build_trie(ss)==1) flag=1;
        }
    }
}