14. Longest Common Prefix

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LeetCode

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Problem

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.

Constraints:

• 1 <= strs.length <= 200
• 0 <= strs[i].length <= 200
• strs[i] consists of only lowercase English letters.

Code

class Solution {
    public String longestCommonPrefix(String[] strs) {
        String pre = strs[0];

        for(int i = 1; i < strs.length; i++){
            while(!strs[i].startsWith(pre)){
                pre = pre.substring(0, pre.length() - 1);
            }
        }

        return pre;
    }
}

class Solution:
    def longestCommonPrefix(self, strs: List[str]) -> str:
        prefix = strs[0]
        for s in strs:
            if s.startswith(prefix):
                continue
            while len(prefix) != 0:
                prefix = prefix[:-1]
                if s.startswith(prefix):
                    break
        return prefix