【leetcode-14】Longest Common Prefix-优快云博客

本文介绍了一种寻找一组字符串中最长公共前缀的算法，通过迭代比较每一对字符串来逐步缩小公共前缀的范围，直至找到最终结果。示例展示了如何在不同输入下应用此算法。

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题目描述

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.

解题思路

思路一：

To employ this idea, the algorithm iterates through the strings [S1…Sn][S_1 \ldots S_n][S1…Sn], finding at each iteration iii the longest common prefix of strings LCP(S1…Si)LCP(S_1 \ldots S_i)LCP(S1…Si) When LCP(S1…Si)LCP(S_1 \ldots S_i)LCP(S1…Si) is an empty string, the algorithm ends. Otherwise after nnn iterations, the algorithm returns LCP(S1…Sn)LCP(S_1 \ldots S_n)LCP(S1…Sn)

代码如下

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if(strs.length==0 || strs == null){
            return "";
        }
        String prefix = strs[0];
        for(int i=1;i<strs.length;i++){
            while(strs[i].indexOf(prefix) != 0){
                prefix = prefix.substring(0,prefix.length()-1);
                if(prefix.isEmpty()){
                    return "";
                }
            }
        }
        return prefix;
    }
}

知识点总结

String 类中的方法indexOf(String s )：当字符串s是调用该方法的字符串的子串时返回0，否则返回-1