[LeetCode] #1248 Count Number of Nice Subarrays

풀이

class Solution {
    public int numberOfSubarrays(int[] nums, int k) {
        HashMap<Integer, Integer> hashMap = new HashMap<>();
        int curr = 0;
        int answer = 0;
        hashMap.put(0,1);
        for(int num: nums) {
            curr += num%2;
            answer += hashMap.getOrDefault(curr - k, 0);
            hashMap.put(curr, hashMap.getOrDefault(curr, 0)+1);
        }
        return answer;
    }
}