String, Hash Tablelink)1
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31class Solution {
static List<Integer> findSubstring(String s, String[] words) {
if(s.length()==0||words.length==0) return new ArrayList();
Map<String,Integer> initial=new HashMap<>();
for(String ss:words) initial.put(ss, initial.getOrDefault(ss, 0)+1);
int len_array=words.length;
int len_single=words[0].length();
int len_str=s.length();
List<Integer> ls=new ArrayList<>();
for(int i=0;i<len_str-len_array*len_single+1;i++){
Map<String,Integer> check=new HashMap<>();
int j=0;
while(j<len_array){
String word=s.substring(i+j*len_single,i+(j+1)*len_single);
if(initial.containsKey(word)){
check.put(word, check.getOrDefault(word,0)+1);
if(check.get(word)>initial.getOrDefault(word,0)) break;
}else{
break;
}
j++;
}
if(j==len_array) ls.add(i);
}
return ls;
}
}