Day-18 Numbers With Same Consecutive Differences

class Solution {
    int n;
    int k;
    List<Integer> result = new ArrayList<>();
    public int[] numsSameConsecDiff(int N, int K) {
        n = N;
        k = K;
        if(n == 1) return new int[]{0,1,2,3,4,5,6,7,8,9};
        for(int i = 1; i < 10; i++) {
            dfs(i, n-1);
        }
        int[] res = new int[result.size()];
        for(int i = 0; i < result.size(); i++) {
            res[i] = result.get(i);
        }
        return res;
    }
    
    public void dfs(int currentNumber, int digitsLeft) {
        if(digitsLeft == 0) {
            result.add(currentNumber);
            return;
        }
        int lastDigit = currentNumber%10;
        if((lastDigit + k) <= 9) {
            dfs(currentNumber * 10 + lastDigit + k, digitsLeft-1);
        }
        if(lastDigit - k >= 0  && k != 0)
            dfs(currentNumber * 10 + lastDigit - k, digitsLeft-1);
    }
}