Leetcode 14. Longest Common Prefix(水)

14. Longest Common Prefix

Easy

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.

class Solution {
public:
    string longestCommonPrefix(vector<string>& strs) {
        int top = 0;
        int fl = 1;
        int len = strs.size();
        if(len==0) return "";
        if(len==1) return strs[0];
        while(fl){
            for (int i = 1 ;i < len; i++){
                if(top>strs[i].length()||top>strs[i-1].length()||strs[i][top]!=strs[i-1][top]){
                    fl = 0;
                    break;
                }
            }
            top++;
        }
        top--;
        if(top==0) return "";
        return strs[0].substr(0,top);
    }
};