Leetcode: 最长公共前缀

题目：编写一个函数来查找字符串数组中的最长公共前缀。
如果不存在公共前缀，返回空字符串 “”。

示例 1：

输入：strs = [“flower”,“flow”,“flight”]
输出：“fl”

示例 2：

输入：strs = [“dog”,“racecar”,“car”]
输出：""
解释：输入不存在公共前缀

提示：

1 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i] 仅由小写英文字母组成

string longestCommonPrefix(vector<string>& strs)
{
	int len1 = (int)strs.size();
	string res = strs[0];
	int len2 = (int)res.size();

	for (int i = 0; i < len2; ++i)
	{
		for (int j = 1; j < len1; ++j)
		{
			if (i == len1 || strs[j][i] != res[i])
			{
				return res.substr(0, i);
			}
		}
	}
	return res;
}

int main()
{
	vector<string> st{ "flower","flow","flight" };
	vector<string> bt{ "dog","dracecar","dcar" };
	auto n = longestCommonPrefix(st);
	auto m = longestCommonPrefix(bt);
	cout << n << endl;
	cout << m << endl;
	return 0;
}