import java.util.HashMap;
import java.util.Map;

public class CosSim {

    public <T>double getSimVal(Map<T,Double> mapA, Map<T,Double> mapB){

        T key;

        double dotProduct = 0.0;
        double sizeA = 0.0;
        double sizeB = 0.0;

        for (Map.Entry<T, Double> entry : mapA.entrySet()) {
            key = entry.getKey();
            if (mapA.containsKey(key) && mapB.containsKey(key)) dotProduct += mapA.get(key) * mapB.get(key);
        }

        for (Map.Entry<T, Double> entry : mapA.entrySet()) {
            key = entry.getKey();
            sizeA += Math.pow(mapA.get(key), 2);
        }

        for (Map.Entry<T, Double> entry : mapB.entrySet()) {
            key = entry.getKey();
            sizeB += Math.pow(mapB.get(key), 2);
        }

        double cosSim = dotProduct / (Math.sqrt(sizeA) * Math.sqrt(sizeB));

        return cosSim;
    }

    private void debug(){
        Map<String, Double> mapA = new HashMap<>();
        mapA.put("リンゴ", 1.0);
        mapA.put("ミカン", 1.0);

        Map<String, Double> mapB = new HashMap<>();
        mapB.put("リンゴ", 1.0);
        mapB.put("バナナ", 1.0);

        double sim = getSimVal(mapA, mapB);
        System.out.println(sim);
    }

    public static void main(String[] args) {
        CosSim cosim = new CosSim();
        cosim.debug();
    }

}