LeetCode [14] Longest Common Prefix

 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: strs = ["flower","flow","flight"]
Output: "fl"

Example 2:

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

 

Constraints:

• 0 <= strs.length <= 200
• 0 <= strs[i].length <= 200
• strs[i] consists of only lower-case English letters.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

class Solution { public: string longestCommonPrefix(vector<string> &strs) { int n = strs.size(); if(n==0) return ""; for(int index = 0; ;index++){ if(strs[0].size()==index) return strs[0].substr(0,index); int c = strs[0][index]; for(int i=1; i<n; ++i){ if(strs[i].size()==index) return strs[0].substr(0,index); if(c!=strs[i][index]) return strs[0].substr(0,index); } } return strs[0]; } };

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

class Solution { public: string longestCommonPrefix(vector<string>& strs) { string ret = ""; int n = strs.size(); if(!n) return ret; int index = 0; while(true){ if(index>=strs[0].size()) return ret; char c = strs[0][index]; for(int i=1; i<n; ++i){ if(index>=strs[i].size() || c!=strs[i][index]) return ret; } ret += c; index++; } } };

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

class Solution { public String longestCommonPrefix(String[] strs) { String r = ""; if(strs.length==0) return r; int index = 0; while(true){ char c = '.'; for(String s : strs){ if(index==s.length()) return r; else if(c!='.' && c!=s.charAt(index)) return r; else{ c = s.charAt(index); } } index++; r += c; } } }