HDU - 1247 Hat’s Words 字典树

/*
Author: 2486
Memory: 9096 KB		Time: 31 MS
Language: G++		Result: Accepted
*/
//这道题目思路非常easy
//就是找两个单词组成还有一个单词就可
#include <cstdio>
#include <vector>
#include <string>
#include <iostream>
#include <queue>
#include <cstring>
#include <algorithm>
using namespace std;
const int MAXN = 1000000 + 5;
const int MAXM = 50000 + 5;
const int INF = 0x3f3f3f3f;
struct node {
    int v,next[30];
    void init() {
        v = -1;
        memset(next, -1, sizeof(next));
    }
} L[MAXN];

int tot;
char str[MAXM][100];
priority_queue<string , vector<string>, greater<string> >P;

void add(char * a, int len) {
    int now = 0;
    for(int i = 0; i < len ; i ++) {
        int tmp = a[i] - 'a';
        int next = L[now].next[tmp];
        if(next == -1) {
            next  = ++ tot;
            L[next].init();
            L[now].next[tmp] = next;
        }
        now = next;
    }
    L[now].v = 0;
}

bool querys(char * a) {
    int len = strlen(a);
    int now  = 0;
    for(int i = 0; i < len; i ++) {
        int tmp = a[i] - 'a';
        int next = L[now].next[tmp];
        if(next == -1) return false;
        now = next;
    }
    return L[now].v == 0;
}

bool query(char * a, int len) {
    int now = 0;
    for(int i = 0; i < len; i ++) {
        int tmp = a[i] - 'a';
        int next = L[now].next[tmp];
        if(L[now].v == 0) {
            if(querys(a + i)) return true;//是否存在还有一个单词能够组成剩下的字符串
        }
        now = next;
    }
    return false;
}

int main() {
    int cnt = 0, Min = INF;
    L[0].init();
    tot = 0;
    //freopen("D://imput.txt", "r", stdin);
    while(~scanf("%s", str[cnt ++])) {
        add(str[cnt - 1], strlen(str[cnt - 1]));
        Min = min(Min, int(strlen(str[cnt - 1])));
    }
    for(int i = 0; i < cnt ; i ++) {
        if(Min * 2 > strlen(str[i]))continue;
        if(query(str[i], strlen(str[i]))) P.push(str[i]);
    }
    string s;
    while(!P.empty()) {//优先队列自己主动排序也可使用set或者map
        s = P.top();
        P.pop();
        cout<<s<<endl;
    }
    return 0;
}