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  1. Sparse Arrays
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Sparse Arrays

  • juanp766
     + 0 comments

    Java using a map to save the frequencies. This solution iterates each list only once.

        public static List<Integer> matchingStrings(List<String> strings, List<String> queries) {
    // Write your code here
        HashMap<String, Integer> stringsMap = new HashMap<>();
        for(String string : strings){
            if(stringsMap.containsKey(string)){
                stringsMap.put(string, stringsMap.get(string) + 1);
            }else{
                stringsMap.put(string, 1);
            }
        }
        
        ArrayList<Integer> results = new ArrayList<>(queries.size());
        for(String query: queries){
            Integer frequency = stringsMap.get(query);
            results.add(frequency == null ? 0 : frequency);
        }
        return results;
    }