leetcode481

public class Solution {
    public int MagicalString(int n) {
        if (n <= ) return ;
            if (n <= ) return ;

            int[] a = new int[n + ];
            a[] = ; a[] = ; a[] = ;
            int head = , tail = , num = , result = ;

            while (tail < n)
            {
                for (int i = ; i < a[head]; i++)
                {
                    a[tail] = num;
                    if (num ==  && tail < n)
                    {
                        result++;
                    }
                    tail++;
                }
                num = num ^ ;//异或
                head++;
            }

            return result;
    }
}

https://leetcode.com/problems/magical-string/#/description