leetcode 14. Longest Common Prefix Javascript

Question

[leetcode problem 14][1] Not understanding why the output is rejected for Longest Common Prefix. Not pasting in the code submission as the problem is my misreading the question.

Wrong Answer

Details 

Input

["reflower","flow","flight"]

Output

"fl"

Expected

""

Description copied from site :

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.

Answer 1

As the problem goes:

... find the longest common prefix string...

You need to find the longest common prefix - which is the string at the beginning of each word.

In your case, the input is ["reflower","flow","flight"].

While flow and flight have the same prefix - fl, reflower doesn't have the same prefix (since it does not start with fl but with re), and as a result the whole 3 words doesn't have a common prefix so the output should be "".

Answer 2

const longestCommonPrefix = function(strs) {
  // const strs = ["flower","flow","flight"];
  // console.log(strs);

  if (!strs.length) return "";

  for (let i = 0; i <= strs[0]; i++) {
    if (!strs.every((string) => string[i] === strs[0][i])) {
      return strs[0].slice(0, i);
    }
  }
  
  return strs[0].slice();
};