Magical String LeetCode solution in Java

1
class Solution {
2
  public int magicalString(int n) {
3
    if (n <= 3) return 1;
4
    Magical m = new Magical();
5
    int ans = 1;
6
    for (int i = 3; i < n; ++i) if (m.next() == 1) ++ans;
7
    return ans;
8
  }
9
}
10

11
class Magical {
12

13
  private Deque<Integer> nums;
14
  private int n;
15

16
  public Magical() {
17
    nums = new ArrayDeque<>();
18
    nums.offerLast(1);
19
    nums.offerLast(1);
20
    n = 1;
21
  }
22

23
  public int next() {
24
    if (n-- < 0) {
25
      int c = nums.pollFirst();
26
      n = c - 2;
27
      int curr = 3 - nums.peekLast();
28
      for (; c > 0; --c) nums.offerLast(curr);
29
      return curr;
30
    }
31
    return nums.peekLast();
32
  }
33
}