14. Longest Common Prefix

• Difficulty: Easy

• Topics: String

• Similar Questions:

Problem:

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string "".

Example 1:

Input: ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Note:

All given inputs are in lowercase letters a-z.

Solutions:

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        string ret;
        if (strs.empty())   return ret;   
        int i = 0;
        while (true) {
            if (i >= strs[0].length())  return ret;
            char commonChar = strs[0][i];
            for (auto& str : strs) {
                if (i >= str.length() || commonChar != str[i])  return ret;
            }
            ret.push_back(commonChar);
            ++i;
        }
    }
};