14. Longest Common Prefix

题目

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:

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

题目大意

编写一个函数来查找字符串数组中的最长公共前缀。

如果不存在公共前缀，返回空字符串 ""。

解题思路

• 对 strs 按照字符串长度进行升序排序，求出 strs 中长度最小字符串的长度 minLen
• 逐个比较长度最小字符串与其它字符串中的字符，如果不相等就返回 commonPrefix,否则就把该字符加入 commonPrefix

代码

package leetcode

import "sort"

func longestCommonPrefix(strs []string) string {
	sort.Slice(strs, func(i, j int) bool {
		return len(strs[i]) <= len(strs[j])
	})
	minLen := len(strs[0])
	if minLen == 0 {
		return ""
	}
	var commonPrefix []byte
	for i := 0; i < minLen; i++ {
		for j := 1; j < len(strs); j++ {
			if strs[j][i] != strs[0][i] {
				return string(commonPrefix)
			}
		}
		commonPrefix = append(commonPrefix, strs[0][i])
	}
	return string(commonPrefix)
}