14. Longest Common Prefix
Write a function to find the longest common prefix string
amongst an array of strings.
题意，找到一组字符串中共同的公共前缀，只需要简单的遍历即可
c++代码：
class Solution {
public:
string longestCommonPrefix(vector<string> &strs) {
if (strs.empty())
return "";
for (int i = 0; i < strs[0].length(); i++) {
for (int j = 1; j < strs.size(); j++)
if (i >= strs[j].length() || strs[j][i] != strs[0][i])
return strs[0].substr(0, i);
}
return strs[0];
}
};
