华为（8）查找两个字符串a,b中的最长公共子串

#include <iostream>
#include <string>
using namespace std;
static string iQueryMaxCommString(string &stringA, string stringB)
{
unsigned int lengthA=stringA.length();
unsigned int lengthB=stringB.length();
unsigned int counts=0;
unsigned int pos_end=0;
for(unsigned int i=0;i<lengthA;++i)
{
unsigned int posA=i;
unsigned int countsA=0;
for(unsigned int j=0;j<lengthB;++j)
{
if(stringA[posA] == stringB[j])
{
++posA;
++countsA;
if(countsA>counts)
{
counts=countsA;
pos_end=posA-1;
}
}
}
}
unsigned int pos_begin=pos_end-counts+1;
string str;
for(unsigned int i=pos_begin;i<=pos_end;++i)
{
str.push_back(stringA[i]);
}
return str;
}

int main()
{
string str1,str2;
getline(cin,str1);
getline(cin,str2);
cout<<iQueryMaxCommString(str1,str2)<<endl;
return 0;
}