串联所有单词的子串(leetcode30)

public class leetcode30 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        String s = "barfoothefoobarman";
        String[] words = new String[]{"foo","bar"};
        
        System.out.println(findSubstring(s,words));
    }

    public static List<Integer> findSubstring(String s, String[] words) {

        List<Integer> res = new ArrayList<Integer>();
        int wordNum = words.length;
        if(wordNum==0){
            return res;
        }
        int wordLen = words[0].length();
        //HashMap1 存所有单词
        HashMap<String,Integer> allWords = new HashMap<String,Integer>();
        for(String w:words){
            Integer value = allWords.get(w);
            allWords.put(w, (value==null?0:value)+1);
        }
        //遍历所有子串
        for(int i=0;i<s.length()-wordNum*wordLen+1;i++){
            //HashMap2 存当前扫描的字符串含有的单词
            HashMap<String,Integer> hasWords = new HashMap<String,Integer>();
            int num =0;
            //判断该子串是否符合
            while(num<wordNum){
                String word = s.substring(i+num*wordLen,i+(num+1)*wordLen);
                //判断该单词在HashMap1 中
                if(allWords.containsKey(word)){
                    Integer value = hasWords.get(word);
                    hasWords.put(word, (value==null?0:value)+1);
                    //判断当前单词的value和HashMap1中的该单词的value
                    if(hasWords.get(word)>allWords.get(word)){
                        break;
                    }
                }else{
                    break;
                }
                num++;
            }
            //判断是不是所有单词都符合条件
            if(num==wordNum){
                res.add(i);
            }
        }
        
        return res;
    }
}