14.LongestCommonPrefix.md

14. Longest Common Prefix

Description

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.

Solution

• java

/*
  Success Details:
  Runtime: 1 ms, faster than 87.55% of Java online submissions for Longest Common Prefix.
  Memory Usage: 36.4 MB, less than 84.85% of Java online submissions for Longest Common Prefix.       
 */
class Solution {
    public String longestCommonPrefix(String[] strs) {
         if (strs == null || strs.length == 0) {
            return "";
        }
        for (int i = 0; i < strs[0].length(); i++) {
            for (int j = 1; j < strs.length; j++) {
                if ((i < strs[j].length() && strs[j].charAt(i) != strs[0].charAt(i)) || i == strs[j].length()) {
                    return strs[0].substring(0, i);
                }
            }
        }
        return strs[0];
    }
}