Problem Description

A hat’s word is a word in the dictionary that is the concatenation of exactly two other words in the dictionary.
You are to find all the hat’s words in a dictionary.

 

Input

Standard
input consists of a number of lowercase words, one per line, in
alphabetical order. There will be no more than 50,000 words.
Only one case.

 

Output

Your output should contain all the hat’s words, one per line, in alphabetical order.

 

Sample Input

 

Sample Output

 

Author

戴帽子的

 

#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

#define FOR(a,b,c) for(int a=(b);a<=(c);a++)

using namespace std;

const int maxl = ;

const int sigmasize = ;

/*

//静态分配内存版本

const int maxnode = 400000;

struct Trie{

    int ch[maxnode][sigmasize];

    int val[maxnode];

    int sz;

    Trie() {

        sz=1;

        memset(ch[0],0,sizeof(ch[0]));

        val[0]=0;

    }

    int idx(char c) { return c-'a'; }

    void insert(char* s,int v) {

        int n=strlen(s),u=0;

        for(int i=0;i<n;i++) {

            int c=idx(s[i]);

            if(!ch[u][c]) {

                memset(ch[sz],0,sizeof(ch[sz]));

                val[sz]=0;

                ch[u][c]=sz++;

            }

            u=ch[u][c];

        }

        val[u]=v;

    }

    int find(char* s) {

        int n=strlen(s),u=0;

        for(int i=0;i<n;i++) {

            int c=idx(s[i]);

            if(!ch[u][c]) return 0;

            else u=ch[u][c];

        }

        return val[u];

    }

}trie;

*/

//动态分配内存版本

struct Node{

    int val;

    Node* next[sigmasize];

};

struct Trie{

    Node *root;

    Trie() {

        root=new Node;

        for(int i=;i<sigmasize;i++) root->next[i]=NULL;

        root->val=;

    }

    int idx(char c) { return c-'a'; }

    void insert(char* s,int v) {

        int n=strlen(s);

        Node* u=root;

        for(int i=;i<n;i++) {

            int c=idx(s[i]);

            if(u->next[c]==NULL) {

                Node* tmp=new Node;

                tmp->val=;

                for(int i=;i<sigmasize;i++) tmp->next[i]=NULL;

                u->next[c]=tmp;

            }

            u=u->next[c];

        }

        u->val=v;

    }

    int find(char* s) {

        int n=strlen(s);

        Node* u=root;

        for(int i=;i<n;i++) {

            int c=idx(s[i]);

            if(u->next[c]==NULL) return ;

            else u=u->next[c];

        }

        return u->val;

    }

    void del(Node *root) {

        for(int i=;i<sigmasize;i++) {

            if(root->next[i]!=NULL) del(root->next[i]);

        }

        free(root);

    }

}trie;

int n=;

char s[][maxl];

int main() {

    //freopen("cin.in","r",stdin);

    //freopen("cout.out","w",stdout);

    while(scanf("%s",s[n])==)    // 注意是scanf==1判断

    {

        trie.insert(s[n],);

        n++;

    }

    char t1[maxl],t2[maxl];

    FOR(i,,n-)

    {

        int len=strlen(s[i]);

        FOR(j,,len-) {

            strcpy(t1,s[i]);

            t1[j]='\0';

            strcpy(t2,s[i]+j);

            if(trie.find(t1) && trie.find(t2)) {

                printf("%s\n",s[i]);

                break;

            }

        }

    }

    trie.del(trie.root);    //内存回收

    return ;

}