leetcode 49. Group Anagrams

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: All inputs will be in lower-case.

将字符串转成字符数组后排序，再转成字符串将其放到map的key中方便进行比对

public class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        Map<String, List<String>> map = new HashMap<>();
        for(String str : strs){
            char[] ca = str.toCharArray();
            Arrays.sort(ca);
            String temp = String.valueOf(ca);
            if(!map.containsKey(temp)) map.put(temp, new ArrayList());
            map.get(temp).add(str);
        }
        return new ArrayList(map.values());
    }
}