Leetcode 268. Missing Number

268. Missing Number

難易度

Easy

アプローチ

Hashmap

class Solution {
    public int missingNumber(int[] nums) {

       HashMap<Integer,Boolean> hashmap = new HashMap<>();

        for(int i = 0 ; i <= nums.length ; i++){
            hashmap.put(i, false);
        }

        Arrays.stream(nums).forEach(obj -> {
            hashmap.put(obj, true);
        });

        return hashmap.entrySet().stream()
                .filter(obj -> obj.getValue() == false)
                .findFirst()
                .get()
                .getKey();
    }
}