HDU 1238 Substrings

Problem Description

You are given a number of case-sensitive strings of alphabetic characters, find the largest string X, such that either X, or its inverse can be found as a substring of any of the given strings.

Input

The first line of the input file contains a single integer t (1 <= t <= 10), the number of test cases, followed by the input data for each test case. The first line of each test case contains a single integer n (1 <= n <= 100), the number of given strings, followed by n lines, each representing one string of minimum length 1 and maximum length 100. There is no extra white space before and after a string. 

Output

There should be one line per test case containing the length of the largest string found.

Sample Input

2

3

ABCD

BCDFF

BRCD

2

rose

orchid

Sample Output

2

2

尋找最長公共子串，反着也行。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
#include<stack>
#include<string>
#include<iostream>
using namespace std;
const int maxn = 105;
int T, n, ans, flag;
string s[maxn], a, b;

bool cmp(const string &a, const string &b)
{
  return a.size() < b.size();
}

int main()
{
  scanf("%d", &T);
  while (T--)
  {
    scanf("%d", &n);
    for (int i = ans = 0; i < n; i++) cin >> s[i];
    sort(s, s + n, cmp);
    for (int i = s[0].size(); i; i--)
      for (int j = 0; s[0][i + j - 1]; j++)
      {
        a = s[0].substr(j, i);
        b.assign(a.rbegin(), a.rend());
        flag = 1;
        for (int k = 1; k < n; k++)
          if (s[k].find(a) == -1 && s[k].find(b) == -1){ flag = 0; break; }
        if (flag) { ans = max(ans, i); goto end; }
      }
    end:printf("%d\n", ans);
  }
  return 0;
}