leetcode-49 Group Anagrams 同位词字典序排序

问题描述:

Given an array of strings,group anagrams together.

For example, given: ["eat", "tea","tan", "ate", "nat", "bat"]
Return:

[

  ["ate","eat","tea"],

 ["nat","tan"],

  ["bat"]

]

Note:

  1. For the return value, each inner list's elements must follow the lexicographic order.
  2. All inputs will be in lower-case.

Update (2015-08-09):
The signature of the function had been updated to return List<List<String>> insteadof List<String>, as suggested here. If you still see your function signature return a List<String>,please click the reload button  to reset your code definition.

 

问题分析:

字典序排序的方法有很多,这里图方便利用了集合中的sort方法进行排序。

查找匹配问题最好使用HashMap;

 

代码:

public class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        List<List<String>>result = new ArrayList<>();
        if(strs == null || strs.length == 0)
           return result;
        //将字典序的字符串作为key,将其同位词组转到一个List中存储到HashMap中
        HashMap<String,List<String>>map = new HashMap<>();
       
        for(int i = 0; i < strs.length; i++) {
           char[] chars = strs[i].toCharArray();
           // 字典序排序
           Arrays.sort(chars);
           String temp = new String(chars);
           
           if (!map.containsKey(temp)) {
               List<String> result_list = new ArrayList<>();
               result_list.add(strs[i]);
               map.put(temp, result_list);
           } else {
               map.get(temp).add(strs[i]);
           }
        }
       
        //遍历map,对ArrayList进行字典序排序
        Iterator<Map.Entry<String,List<String>>>iterator = map.entrySet().iterator();
        while(iterator.hasNext()) {
           Map.Entry<String,List<String>> entry = iterator.next();
           List<String> temp_list = entry.getValue();
           Collections.sort(temp_list);
           result.add(temp_list);
        }       
        return result;
    }
}


你可能感兴趣的:(leetcode-49 Group Anagrams 同位词字典序排序)