CountWordsObtainedAfterAddingALetter.java

 class Solution {
     public int wordCount(String[] startWords, String[] targetWords) {
         Set<String> set=new  HashSet();
         for(String s: startWords){
             char[] charStr=s.toCharArray();
             Arrays.sort(charStr);
             // will store all the strings in stored order
             set.add(new String(charStr));
         }
         int count=0;
         for(String t: targetWords){
             int n = t.length();
             for(int i=0;i<n;i++){
                 String reducedStr= t.substring(0, i) + t.substring(i+1); // skip ith index
                 char[] charStr =reducedStr.toCharArray();
                 Arrays.sort(charStr);
                 String storedStr = new String(charStr);
                 if(set.contains(storedStr)){
                     count++;
                     break;
                 }
             }
         }
         return count;
     }
 }


class Solution {
	public int wordCount(String[] startWords, String[] targetWords) {
		int ans = 0;
		Set<Integer> seen = new HashSet<>();
		for (String word : startWords) {
			seen.add(bitmask(word));
		}

		for (String word : targetWords) {
			int bitmask = bitmask(word);
			for (char c : word.toCharArray()) {
				if (seen.contains(bitmask - (1 << c - 'a'))) {
					ans++;
					break;
				}
			}
		}
		return ans;
	}

	//ad
	// 32
	//     00000001001
	private int bitmask(String word) {
		int res = 0;
		for (char c : word.toCharArray()) {
			res += 1 << c - 'a';
		}
		return res;
	}
}