[LC] 14. Longest Common Prefix

Posted 2020-11-22 xuanlu

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.

 

Time: O(M * N)

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if (strs == null || strs.length == 0) {
            return "";
        }
        int len = strs[0].length();
        for (int i = 0; i < len; i++) {
            char cur = strs[0].charAt(i);
            for (int j = 1; j < strs.length; j++) {
                if (i == strs[j].length() || strs[j].charAt(i) != cur) {
                    return strs[0].substring(0, i);
                }
            }
        }
        return strs[0];
    }
}