POJ 1056

#include <iostream>
#include <string>
#define MAXN 50
using namespace std;

struct node
{
    node * l;
    node * r;
    bool boo;
    node()
    {
        l = NULL;
        r = NULL;
        boo = false;
    }
};


bool ans;

int _index;

node res[2*MAXN+1];

node * insert(node * root,string s,int index,int len)
{
    if(s[index] == '0')
    {
        if(root->l == NULL)
        {
            root->l = &res[_index ++];
            root->l->boo = false;
            root->l->l = root->l->r = NULL;
            if(index == len-1)
            {
                root->l->boo = true;
                return root;
            }
        }
        else
        {
            if(index == len-1)
            {
                ans = false;
                return root;
            }
            if(root->l->boo == true)
            {
                ans = false;
                return root;
            }
        }


        root->l = insert(root->l,s,index+1,len);
        return root;
    }
    else
    {
        if(root->r == NULL)
        {
            root->r = &res[_index ++];
            root->r->boo = false;
            root->r->l = root->r->r = NULL;
            if(index == len-1)
            {
                root->r->boo = true;
                return root;
            }
        }
        else
        {
            if(index == len-1)
            {
                ans = false;
                return root;
            }
            if(root->r->boo == true)
            {
                ans = false;
                return root;
            }
        }
        root->r = insert(root->r,s,index+1,len);
        return root;
    }
}

int main()
{
    //freopen("acm.acm","r",stdin);
    string s;
    int time = 0;
    while(cin>>s)
    {
        _index = 0;
        ans = true;
        node * root = &res[_index ++];
        root->boo = false;
        root->l = root->r = NULL;
        if(ans)
        {
            root = insert(root,s,0,s.length());
        }
        while(cin>>s)
        {
            if(s == "9")
            {
                break;
            }
            if(ans)
            {
                root = insert(root,s,0,s.length());
            }
        }
        cout<<"Set "<<++ time;
        if(ans == false)
        {
            cout<<" is not immediately decodable"<<endl;
        }
        else
        {
            cout<<" is immediately decodable"<<endl;
        }
    }
}

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