Question:

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

Solution:

  1. /**
  2.  * @param {string[]} strs
  3.  * @return {string}
  4.  */
  5. var longestCommonPrefix = function(strs) {
  6.   const start = strs[0];
  7.   const result = [];
  9.   let vaild = function (index) {
  10.     for (let j = 1 ; j < strs.length; j++) {
  11.       if (strs[0].charAt(index) != strs[j].charAt(index)) {
  12.         return false;
  13.       }
  14.     }
  15.     return true;
  16.   }
  18.   for (let i in start) {
  19.     if (!vaild(i)) break;
  20.     result.push(start.charAt(i));
  21.   }
  23.   return result.join('');
  24. };

Runtime: 60 ms, faster than 52.23% of JavaScript online submissions for Longest Common Prefix.