49. Group Anagrams

 

一次遍历，用一个map记录相同的string <String, List<String>>

char[]到String 用new String()

 

class Solution {
    public List<List<String>> groupAnagrams(String[] strs) {
        List<List<String>> res = new ArrayList<>();
        if(strs.length == 0) return res;
        HashMap<String, List<String>> map = new HashMap<>();
        for(int i = 0; i < strs.length; i++){
            char[] arr = strs[i].toCharArray();
            Arrays.sort(arr);
            String str = new String(arr);
            if(map.containsKey(str)){
                List<String> list = map.get(str);
                list.add(strs[i]);
                map.put(str, list);
            }else{
                List<String> list = new ArrayList<>();
                list.add(strs[i]);
                map.put(str, list);
            }
        }
        for(String str : map.keySet()){
            res.add(map.get(str));
        }
        return res;
        
    }
}