481. 神奇字符串

神奇字符串

题解：模拟这个神奇字符串，然后直接统计1的个数即可

class Solution {
    public int magicalString(int n) {
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append(12);
        boolean flag = false;
        Queue<Integer> queue = new ArrayDeque<>();
        queue.offer(1);
        int res = 1;
        while(stringBuilder.length() < n) {
            int len = queue.remove();
            for(int i = 0 ; i < len && stringBuilder.length() < n; i++) {
                stringBuilder.append(flag ? 1 : 2);
                queue.add(flag ? 1 : 2);
                res += flag ? 1 : 0;
            }
            flag = !flag;
        }
        return res;
    }
}