[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];
}
};