求最大公共子串

#include <stdio.h>
#include <stdlib.h>
#include <string>

using namespace std;

struct stringtag
{
	string value;
	int tag;
};

int stringcompare(const void* A,const void* B)
{
	struct stringtag* AA = (struct stringtag*)A;
	struct stringtag* BB = (struct stringtag*)B;
	return (*AA).value.compare( (*BB).value);
}

int cutstring(struct stringtag strarr[],int arrsize,string sourcestr,int tag)
{
	int i = 0;
	for(; i < arrsize && i < sourcestr.length(); i ++){
		strarr[i].tag = tag;
		strarr[i].value = sourcestr.substr(i);
	}
	return i;
}
int getmatchstr(struct stringtag A,struct stringtag B)
{
	int i = 0;
	for(; i < A.value.length() && i < B.value.length();i ++)
		if(A.value.c_str()[i] != B.value.c_str()[i]) break;
	return i;
}

int main(int argc,char* argv[])
{
	string testa = "awerdasadfdfdfqedfjhoqewhjkhadsf";
	string testb = "weqwdadfefdzxcverqrjhr";
	struct stringtag aArr[100] = {""};

	int len = cutstring(aArr,100,testa,0);
	len = cutstring(aArr+len,100 -len,testb,1) + len;
	qsort(aArr,len,sizeof(struct stringtag),stringcompare);
	int matchlen = 0,maxindex = 0;

	for(int i = 0; i < len -1; i ++ )
	{
		if(aArr[i].tag != aArr[i+1].tag)
		{
			int tmplen = getmatchstr(aArr[i],aArr[i+1]);
			if(tmplen > matchlen) 
			{
				matchlen = tmplen;
				maxindex = i;
			}
		}
	}
	printf("max common substr:%s \n",aArr[maxindex].value.substr(0,matchlen).c_str());
	return 0;
}