pat 1077 Kuchiguse（20 分） (字典树)

1077 Kuchiguse（20 分）

The Japanese language is notorious for its sentence ending particles. Personal preference of such particles can be considered as a reflection of the speaker's personality. Such a preference is called "Kuchiguse" and is often exaggerated artistically in Anime and Manga. For example, the artificial sentence ending particle "nyan~" is often used as a stereotype for characters with a cat-like personality:

• Itai nyan~ (It hurts, nyan~)

• Ninjin wa iyada nyan~ (I hate carrots, nyan~)

Now given a few lines spoken by the same character, can you find her Kuchiguse?

Input Specification:

Each input file contains one test case. For each case, the first line is an integer N (2≤N≤100). Following are N file lines of 0~256 (inclusive) characters in length, each representing a character's spoken line. The spoken lines are case sensitive.

Output Specification:

For each test case, print in one line the kuchiguse of the character, i.e., the longest common suffix of all N lines. If there is no such suffix, writenai.

Sample Input 1:

3
Itai nyan~
Ninjin wa iyadanyan~
uhhh nyan~

Sample Output 1:

nyan~

Sample Input 2:

3
Itai!
Ninjinnwaiyada T_T
T_T

Sample Output 2:

nai

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <string>
#include <map>
#include <stack>
#include <vector>
#include <queue>
#include <set>
#define LL long long
#define INF 0x3f3f3f3f
using namespace std;
const int MAX = 1e5 + 10;

int n, rt = 0, str_len = INF;
struct node
{
    int id, cnt, next[128];
} P[MAX];
char shortest_str[300];
stack <char> st;

void init(int x)
{
    for (int i = 0; i <= 127; ++ i)
        P[x].next[i] = -1;
}

void my_insert(char *S, int len, int x)
{
    int now = 0;
    for (int i = 0; i < len; ++ i)
    {
        if (P[now].next[S[i]] == -1)
        {
            P[now].next[S[i]] = ++ rt;
            init(rt);
        }
        now = P[now].next[S[i]];
        P[now].cnt ++;
    }
}

int my_find(int len)
{
    int now = 0;
    for (int i = 0; i < len; ++ i)
    {
        if (P[now].next[shortest_str[i]] == -1) return -1;
        now = P[now].next[shortest_str[i]];
    }
    return P[now].cnt;
}

int main()
{
//    freopen("Date1.txt", "r", stdin);
    scanf("%d", &n);
    init(0);
    getchar();
    for (int i = 0; i < n; ++ i)
    {
        char buf[300];
        string temp;
        getline(cin, temp);
        int len = temp.size();
        for (int j = 0, k = len - 1; k >= 0; -- k, ++ j)
            buf[j] = temp[k];
        buf[len] = '';
        my_insert(buf, len, i);
        if (len < str_len)
        {
            str_len = len;
            strcpy(shortest_str, buf);
        }
    }

    if (P[P[0].next[shortest_str[0]]].cnt != n)
    {
        printf("nai
");
        return 0;
    }
    for (int i = str_len; i >= 1; -- i)
    {
        if (my_find(i) == n)
        {
            for (int j = 0; j < i; ++ j)
                st.push(shortest_str[j]);
            break;
        }
    }
    while (st.size())
    {
        printf("%c", st.top());
        st.pop();
    }

    return 0;
}