The Dominator of Strings

最新推荐文章于 2022-07-22 19:14:00 发布

Jade1998

最新推荐文章于 2022-07-22 19:14:00 发布

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Time Limit: 3000/3000 MS (Java/Others) Memory Limit: 65535/32768 K (Java/Others)

Total Submission(s): 515 Accepted Submission(s): 146

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

Source

2017 ACM/ICPC Asia Regional Qingdao Online

唉，，，，好坑啊，开始用ac自动机，要不超内存，要不就超时，挑了将近两三个小时，没ac，比赛结束，听说用kmp就能过，然后试了下，AC

代码如下：

#include <iostream>  
#include <cstdio>  
#include <stdlib.h>
#include <cstring>  
#include <queue>  
using namespace std;
int kmp_find(const char* target,const char* pattern)
{
    const int target_length = strlen(target);
    const int pattern_length = strlen(pattern);
    int * overlay_value = new int[pattern_length];
    overlay_value[0] = -1;//存前缀和后缀相同元素的长度
    int index = 0;
    for(int i=1;i<pattern_length;++i)
    {
        index = overlay_value[i-1];
        while(index>=0 && pattern[index+1]!=pattern[i])
        {
            index  = overlay_value[index];
        }
        if(pattern[index+1]==pattern[i])
        {
            overlay_value[i] = index +1;
        }
        else
        {
            overlay_value[i] = -1;
        }
    }

    //match algorithm start
    int pattern_index = 0;
    int target_index = 0;
    while(pattern_index<pattern_length&&target_index<target_length)
    {
        if(target[target_index]==pattern[pattern_index])
        {
            ++target_index;
            ++pattern_index;
        }
        else if(pattern_index==0)
        {
            ++target_index;
        }
        else
        {
            pattern_index = overlay_value[pattern_index-1]+1;
        }
    }
    delete [] overlay_value;
    if(pattern_index==pattern_length)
    {
        return target_index-pattern_index;
    }
    else
    {
        return -1;
    }
   
}  
char s[200002];
char* p[100005];
int main()  
{  
    int t,n,m,len,i; 
    scanf("%d",&t);  
    while(t--)  
    {  
    	scanf("%d",&n);
    	memset(s,'\0',sizeof(s));
    	len=m=0;
    	p[0]=s;
    	for(int i=0;i<n;i++)
    	{
    		scanf("%s",p[i]);
    		if(strlen(p[i])>len)
		{
			len=strlen(p[i]);
			m=i;
		} 
    		p[i+1]=p[i]+strlen(p[i])+1; 
	}
        int ans=0;
	for(int i=0;i<n;i++)
	{
		if(i!=m&&kmp_find(p[m],p[i])!=-1)
			ans++;
	}
	if(ans==n-1)
		printf("%s\n",p[m]);
	else
		printf("No\n");
    }  
    return 0;  
}