Substrings （C++ find函数应用）

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（相反，倒转） 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

 

题目意思：找出所给字符串的最大公共子串，这个公共子串可以翻转存在于母串之中。

解题思路：我在这里直接使用了C++ string 中的一些函数处理的，比使用C的逐个字符的遍历好写一些。

贴一篇关于find函数的说明：https://www.cnblogs.com/wkfvawl/p/9429128.html

#include <iostream>
#include <string>
#include <algorithm>
#define INF 0x3f3f3f3f
using namespace std;

int main()
{
    int t,n,i,j,k;
    int mins;
    int pos,flag,flag1;
    string s[];
    string key;
    string tem;
    string rev;
    cin>>t;
    while(t--)
    {
        cin>>n;
        pos=;
        flag=;
        mins=INF;
        for(i=;i<n;i++)
        {
            cin>>s[i];
            if(s[i].length()<mins)
            {
                mins=s[i].length();
                pos=i;
            }
        }
        key=s[pos];
        for(i=mins;i>=;i--)//子串长度
        {
            for(j=;j+i-<mins;j++)
            {
                tem=key.substr(j,i);//截取以j开头长度为i的子串
                rev=string(tem.rbegin(),tem.rend());//反向迭代器，翻转后的子串
                flag=;
                flag1=;
                for(k=;k<n;k++)
                {
                   if(s[k].find(tem)==string::npos&&s[k].find(rev)==string::npos)
                   {
                       flag=;
                       break;
                   }//没有找到这样一个子串
                }
                if(flag)//找到了一个子串
                {
                    cout<<i<<endl;
                    flag1=;
                    break;
                }
            }
            if(!flag1)
            {
                break;
            }
        }
        if(flag1)
        {
            cout<<<<endl;
        }
    }
    return ;
}