[프로그래머스 Lv.1] 없는 숫자 더하기

 

 

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

class Solution {
    public int solution(int[] numbers) {
        Map<Integer, Boolean> numberMap = initNumberMap(numbers);
        int sumOfExceptNum = 0;
        for (int i = 0; i < 10; i++) {
            if (numberMap.containsKey(i)) {
                continue;
            }
            sumOfExceptNum += i;
        }
        return sumOfExceptNum;
    }

    private HashMap<Integer, Boolean> initNumberMap(int[] numbers) {
        HashMap<Integer, Boolean> numberMap = new HashMap<>();
        for (int number : numbers) {
            numberMap.put(number, true);
        }
        return numberMap;
    }
}