leetcode 14. Longest Common Prefix

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.

思路：直接判断每一个位置是否字符相同，直到不同。

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        int len = strs.size();
        if (len == 0)
            return "";
        for (int i = 0; i < strs[0].length(); ++i) {
            char c = strs[0][i];
            for (int j = 1; j < strs.size(); ++j) {
                if (i < strs[j].length() && strs[j][i] == c) {
                    continue;
                } else {
                    return strs[0].substr(0, i);
                }
            }
        }
        return strs[0];
    }
};