[LintCode] 最长公共前缀

class Solution {
public:    
    /**
     * @param strs: A list of strings
     * @return: The longest common prefix
     */
    string longestCommonPrefix(vector<string> &strs) {
        // write your code here
        string lcp = "";
        if (strs.empty()) return lcp;
        for (int i = 0; i < (int)strs[0].length(); i++) {
            int pos = lcp.length();
            char letter = strs[0][pos];
            for (int j = 1; j < (int)strs.size(); j++)
                if (strs[j].length() == pos || strs[j][pos] != letter)
                    return lcp;
            lcp += letter;
        }
        return lcp;
    }
};