GroupAnagrams.java

package other;

import java.util.*;

/**
 * @Author: Wenhang Chen
 * @Description:给定一个字符串数组，将字母异位词组合在一起。字母异位词指字母相同，但排列不同的字符串。 示例:
 * <p>
 * 输入: ["eat", "tea", "tan", "ate", "nat", "bat"],
 * 输出:
 * [
 * ["ate","eat","tea"],
 * ["nat","tan"],
 * ["bat"]
 * ]
 * @Date: Created in 8:44 1/12/2020
 * @Modified by:
 */
public class GroupAnagrams {
    public List<List<String>> groupAnagrams(String[] strs) {
        if (strs.length == 0) return new ArrayList();
        Map<String, List> ans = new HashMap<String, List>();
        int[] count = new int[26];
        for (String s : strs) {
            Arrays.fill(count, 0);
            for (char c : s.toCharArray()) count[c - 'a']++;

            StringBuilder sb = new StringBuilder("");
            for (int i = 0; i < 26; i++) {
                sb.append('#');
                sb.append(count[i]);
            }
            String key = sb.toString();
            if (!ans.containsKey(key)) ans.put(key, new ArrayList());
            ans.get(key).add(s);
        }
        return new ArrayList(ans.values());
    }
}