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 + ;

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

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

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

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

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

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

     return ;
 }