> For the complete documentation index, see [llms.txt](https://dfine.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dfine.gitbook.io/leetcode/953.verifying_an_alien_dictionary.md).

# 953.Verifying an Alien Dictionary

**953.Verifying an Alien Dictionary**

难度:Easy

> 某种外星语也使用英文小写字母，但可能顺序 order 不同。字母表的顺序（order）是一些小写字母的排列。

给定一组用外星语书写的单词 words，以及其字母表的顺序 order，只有当给定的单词在这种外星语中按字典序排列时，返回 true；否则，返回 false。

```
示例 1：

输入：words = ["hello","leetcode"], order = "hlabcdefgijkmnopqrstuvwxyz"
输出：true
解释：在该语言的字母表中，'h' 位于 'l' 之前，所以单词序列是按字典序排列的。
示例 2：

输入：words = ["word","world","row"], order = "worldabcefghijkmnpqstuvxyz"
输出：false
解释：在该语言的字母表中，'d' 位于 'l' 之后，那么 words[0] > words[1]，因此单词序列不是按字典序排列的。
示例 3：

输入：words = ["apple","app"], order = "abcdefghijklmnopqrstuvwxyz"
输出：false
解释：当前三个字符 "app" 匹配时，第二个字符串相对短一些，然后根据词典编纂规则 "apple" > "app"，因为 'l' > '∅'，其中 '∅' 是空白字符，定义为比任何其他字符都小（更多信息）。
 

提示：

1 <= words.length <= 100
1 <= words[i].length <= 20
order.length == 26
在 words[i] 和 order 中的所有字符都是英文小写字母。
```

建立比较函数。

```
class Solution {
private:
   unordered_map<char,int>ord;
    bool comp(string a, string b)
    {
        int n =min(a.length(),b.length());
        for(int i=0;i<n;i++)
        {
            if(ord[a[i]] <ord[b[i]]) return true;
            else if(ord[a[i]]>ord[b[i]]) return false;
        }
        return a.length() < b.length();
        
        
    }
public:
    bool isAlienSorted(vector<string>& words, string order) {

        int i=0;
        for(char c: order)
            ord[c]=i++;
        for(i=1;i<words.size();i++)
            if(comp(words[i],words[i-1])) return false;
        return true;
    }
};
```

> 执行用时 : 20 ms, 在Verifying an Alien Dictionary的C++提交中击败了40.66% 的用户\
> 内存消耗 : 9.6 MB, 在Verifying an Alien Dictionary的C++提交中击败了70.21% 的用户


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