输入3个子串， 输出这3个子串的最大公共子串

#include <iostream>
#include <string>
using namespace std;
int main()
{
	string s1;
	string s2;
	string s3;
	string *sp1;
	string *sp2;
	string *minp;
	cin>>s1>>s2>>s3;
	if(s1.length()> s2.length())
	{
		sp1 = &s1;
		sp2 = &s2;	
	}else
	{
		sp1 = &s2;
		sp2 = &s1;
	}
	
	if(sp2->length()>s3.length())
	{
		minp = &s3;
	}else
	{
		minp = sp2;
		sp2 = &s3;
	}
	
	int max = 0;
	int start = 0;
	int length = minp->length();
	for(int i = 0; i < length; ++i )
	{
		int templen = length - i;
		for(int n = max; n < templen; ++n)
		{
			if((sp1->find(minp->substr(i, n))!=string::npos) && (sp2->find(minp->substr(i, n))!= string::npos))
			{
				if(n > max)
				{
					max = n;
					start = i;
				}
			}else
			{
				break;
			}
		}
	}
	cout<<minp->substr(start, max);
	return 0;
}