difficulty: medium
given an array of strings, group anagrams together.
example:
input: ["eat", "tea", "tan", "ate", "nat", "bat"],
output:
[
["ate","eat","tea"],
["nat","tan"],
["bat"]
]
note:
- all inputs will be in lowercase.
- the order of your output does not matter.
language: java
class Solution {
public List<List<String>> groupAnagrams(String[] strs) {
List<List<String>> resultList = new ArrayList<>();
if (strs == null || strs.length == 0) {
return resultList;
}
Map<String,List<String>> groupsMap = new HashMap<>();
// 这里的 key 需要是 String，而不能使用数组，如果使用数组的话，key是内存地址，无法满足要求。
// value 存储的是这个组的字符串的 index
for (int i = 0; i < strs.length; i++) {
String str = strs[i];
char[] chars = str.toCharArray();
Arrays.sort(chars);
String s = String.valueOf(chars); // 排序后得到最新的字符串
if (groupsMap.containsKey(s)) {
groupsMap.get(s).add(str);
continue;
}
List<String> resultItem = new ArrayList<>();
groupsMap.put(s,resultItem);
resultItem.add(str);
resultList.add(resultItem);
}
return resultList;
}
}