题解 | #整数中1出现的次数（从1到n整数中1出现的次数）#

虽然很low，但是直接嗷

    public int NumberOf1Between1AndN_Solution(int n) {
        int  i = 1;
        int res = 0;
        while (i <= n){
            int cur = (i + "a").split("1").length - 1;
            res += cur;
            i++;
        }
        return res;
    }