Stickers to Spell Word.java

class Solution {
    HashMap<String,HashMap<Character,Integer>>map;
    public int minStickers(String[] stickers, String target) {
        map = new HashMap<>();
        for(String sticker:stickers){
            HashMap<Character,Integer> temp = new HashMap<>();
            for(char ch:sticker.toCharArray())
                temp.put(ch,temp.getOrDefault(ch,0)+1);
            map.put(sticker,temp);
        }
        int count = memoization(target,new HashMap<>());
        return count<1||count>=Integer.MAX_VALUE?-1:count;
    }
    public int memoization(String target, HashMap<String, Integer>dpmap){
        if(target.length()==0)return 0;
        if(dpmap.containsKey(target)) return dpmap.get(target);
        int count = Integer.MAX_VALUE;
        for(String str: map.keySet()){
              HashMap<Character,Integer> xd = new HashMap(map.get(str));
              String temp = target;
              char ch = temp.charAt(0);
              if(xd.containsKey(ch)){
                 for(int i =0;i<temp.length();i++){
                     ch = temp.charAt(i);
                     if(xd.containsKey(ch) && xd.get(ch)>0){
                         xd.put(ch,xd.get(ch)-1);
                         temp = temp.substring(0,i)+temp.substring(i+1);
                         i--;
                     }
                 }
                  if(temp.length()!=target.length()){
                      count  = Math.min(count,1+memoization(temp,dpmap));
                      dpmap.put(target,count);    
                  }
              }
        }
        return count;
    }
}