[LintCode] Longest Common Prefix 最长共同前缀

Given k strings, find the longest common prefix (LCP).

Have you met this question in a real interview?

 

 

Example

For strings "ABCD", "ABEF" and "ACEF", the LCP is "A"

For strings "ABCDEFG", "ABCEFG" and "ABCEFA", the LCP is "ABC"

LeetCode上的原题，请参见我之前的博客Longest Common Prefix。

解法一：

class Solution {
public:    
    /**
     * @param strs: A list of strings
     * @return: The longest common prefix
     */
    string longestCommonPrefix(vector<string> &strs) {
        if (strs.empty()) return "";
        string res = "";
        for (int j = 0; j < strs[0].size(); ++j) {
            char c = strs[0][j];
            for (int i = 0; i < strs.size(); ++i) {
                if (j >= strs[i].size() || strs[i][j] != c) return res;
            }
            res.push_back(c);
        }
        return res;
    }
};

解法二：

class Solution {
public:    
    /**
     * @param strs: A list of strings
     * @return: The longest common prefix
     */
    string longestCommonPrefix(vector<string> &strs) {
        if (strs.empty()) return "";
        for (int j = 0; j < strs[0].size(); ++j) {
            for (int i = 0; i < strs.size() - 1; ++i) {
                if (j >= strs[i].size() || j >= strs[i + 1].size() || strs[i][j] != strs[i + 1][j]) {
                    return strs[i].substr(0, j);
                }
            }
        }
        return strs[0];
    }
};