最长的连续相同字符的字符串和最长连续不相同字符的子字符串问题

1、给定一个字符串s，获取其最长的连续相同字符的子字符串，实现代码如下

#include<iostream>
#include<string>
using namespace std;
string longestSameCharacter(string &s)
{
	int slen = s.length();
	if (slen == 0)
	{
		return "";
	}
	int first = 0;
	int len = 1;
	int maxfirst = 0;
	int maxlen = 1;
	int i = 1;
	while (i != slen)
	{
		if (s[i] == s[i - 1])
		{
			len = i - first + 1;
			if (len > maxlen)
			{
				maxfirst = first;
				maxlen = len;
			}
		}
		else
		{
			first = i;
		}
		++i;
	}
	return s.substr(maxfirst, maxlen);
}
int main()
{
	string s1 = "a";
	string s2 = "abgakgsaksse";
	string s3 = "abccccccccf";
	string s4 = "ahiengkehkigfioaa";
	cout << longestSameCharacter(s1) << endl;
	cout << longestSameCharacter(s2) << endl;
	cout << longestSameCharacter(s3) << endl;
	cout << longestSameCharacter(s4) << endl;
	system("pause");
	return 0;
}#inclu