LeetCode-14-longest-common-prefix | 最长公共前缀

题目

LeetCode
LeetCode-cn

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.

题解

这道题目的简单描述就是找一堆字符串的相同前缀，比如flower、flow、flight，发现每个字符串都有前缀fl，于是就将fl返回即可，本题就是要实现这样一个在字符串数组中找最长前缀的函数。

解法一：暴力

//Go
func longestCommonPrefix(strs []string) string {
	//排除特殊情况
	if len(strs) == 0 {
		return ""
	}
	if len(strs) == 1 {
		return strs[0]
	}
	res := strs[0]               //获取字符串数组里的第一个元素
	for _, v := range strs[1:] { //从字符串数组第二个元素开始遍历
		var i int
		for ; i < len(v) && i < len(res); i++ { //遍历两数组里的元素
			if res[i] != v[i] { //做判断，如果不相等
				break //直接结束循环
			}
		}
		res = res[:i]
		if res == "" {
			return res //返回空
		}
	}

	return res
}

另一种相似解法，会用到strings.Index

//Go
func longestCommonPrefix(strs []string) string {
    if len(strs) < 1 {
        return ""
    }
    prefix := strs[0]
    for _,k := range strs {
        for strings.Index(k,prefix) != 0 {
            if len(prefix) == 0 {
                return ""
            }
            prefix = prefix[:len(prefix) - 1]
        }
    }
    return prefix
}

执行结果：

力扣：
执行用时：0 ms, 在所有 Go 提交中击败了100.00%的用户
内存消耗：2.3 MB, 在所有 Go 提交中击败了55.76%的用户

leetcode：
Runtime: 0 ms, faster than 100.00% of Go online submissions for Longest Common Prefix.
Memory Usage: 2.4 MB, less than 100.00% of Go online submissions for Longest Common Prefix.

参考题解

力扣官方题解-5种解法