简单题 懒得多说了，反正也没人会看。

bool func1(vector<string>& strs, int sht) {
	char s = strs[0][sht];
	for (int i = 1; i < strs.size(); ++i) {
		if (s != strs[i][sht])
			return false;
	}
	return true;
}


string longestCommonPrefix(vector<string>& strs) {
	int back = 0, sht = INT_MAX, sz = strs.size();
	if (!sz)
		return string();
	else if (sz == 1)
		return strs[0];
	for (int i = 0; i < sz; ++i)
		if (sht > strs[i].size())
			sht = strs[i].size();
	for (int i = 0; i < sht; ++i)
		if (!func1(strs, i))
			return strs[0].substr(0, i);
	return strs[0].substr(0, sht);
}