Group Anagrams
给一个字符串组, 把其中的anagrams成组. 这个题用hash来找, 因为知道anagram就是把一个字符串打散. 所以他们的hash都相同.
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public class Solution { private int hash(int[] count) { int a = 3; int b = 7; int hash = 0; for(int n : count) { hash = hash*a + n; a = a * b; } return hash; } public ArrayList<String> anagrams(String[] strs) { if(strs.length == 0 || strs == null) return null; HashMap<Integer,ArrayList<String>> m = new HashMap<Integer, ArrayList<String>>(); for(String s : strs) { int[] count = new int[26]; for(int i = 0 ; i < s.length(); i++){ count[s.charAt(i) - 'a'] ++; } int h = hash(count); if(!m.containsKey(h)){ m.put(h, new ArrayList<String>()); } m.get(h).add(s); } ArrayList<String> res = new ArrayList<String>(); for(ArrayList<String> ary : m.values()){ if(ary.size() > 1) res.addAll(ary); } return res; } } |