HDU–6208 The Dominator of Strings[KMP]

Posted 2020-10-09 zprhhs

The Dominator of Strings

Problem Description

Here you have a set of strings. A dominator is a string of the set dominating all strings else. The string S is dominated by T if S is a substring of T.

Input

The input contains several test cases and the first line provides the total number of cases.
For each test case, the first line contains an integer N indicating the size of the set.
Each of the following N lines describes a string of the set in lowercase.
The total length of strings in each case has the limit of 100000.
The limit is 30MB for the input file.

Output

For each test case, output a dominator if exist, or No if not.

Sample Input

3
10
you
better
worse
richer
poorer
sickness
health
death
faithfulness
youbemyweddedwifebetterworsericherpoorersicknesshealthtilldeathdouspartandpledgeyoumyfaithfulness
5
abc
cde
abcde
abcde
bcde
3
aaaaa
aaaab
aaaac

Sample Output

youbemyweddedwifebetterworsericherpoorersicknesshealthtilldeathdouspartandpledgeyoumyfaithfulness
abcde
No
题意：所给的所有字符串中是否含有一个主串包含其他的字符串。
思路：直接找到最长的，检查。
#include "bits/stdc++.h"
using namespace std;
const int maxn = 2000000 + 10;
int f[maxn];
int T,N;
char s[maxn];
char *t[maxn];
void getfail(char p[]) {
    int len = strlen(p);  
    f[0] = f[1] = 0;  
    for(int i = 1; i < len; i++) {
        int j = f[i];  
        while(j and p[i] != p[j]) j = f[j];  
        if(p[i] == p[j]) f[i + 1] = j + 1; 
        else f[i + 1] = 0;   
    }   
}  
int find(char T[], char P[]) {
    int n = strlen(T), m = strlen(P);    
    getfail(P); int j = 0;  
    for(int i = 0; i < n; i++) {
        while(j && P[j] != T[i]) j = f[j];    
        if(P[j] == T[i]) j++; 
        if(j == m) return 1;
    }    
    return -1;    
} 
int main(int argc, char const *argv[])
{
    scanf("%d",&T);
    while(T--){
        scanf("%d",&N);
        int maxx = 0;
        int tlen = 0;
        char *ms, *ts=s;
        for(int i=1 ;i <= N;i++){
            scanf("%s",ts);
            tlen = strlen(ts);
            if(tlen > maxx){
                maxx = tlen; ms = ts;
            }
            t[i] = ts; ts += strlen(ts) + 2;
        }
        bool flag = true;
        for(int j = 1;j <= N; j++){
            if( find(ms,t[j]) != 1 ){
                flag = false; break;
            }
        }
        if(flag) printf("%s\n",ms);
        else printf("No\n");
    }
    return 0;
}