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.

自己写的时候总是各种边界条件没有检查到.

这个思路还不错,并不是采用取出第i个字符,然后逐一比较, 直接把第一个字符串的长度作为循环条件

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        if(strs.empty())return string();
        string res;
        for(int i=0;i<strs[0].size();++i)
        {
            int j=1;
            for(;j<strs.size()&&strs[j].size()>i;++j)
                if(strs[j][i]!=strs[0][i]) return res;
            if(j==strs.size())
                res+=strs[0][i];
        }
        return res;
    }
};