昨天看同事面试，里面有道题觉得挺有意思。如题：输入一个数如12， 检查里面1出现过几次（1,10,11,12）共出现5处1，其中11为两次。

        public staticint SumNumber(int n)

        {

            if (n < 0)

                return -1;

            if (n < 10)

                return n;

            int count = 0;

            while (n > 0)

            {

                int temp = n % 10;

                int temp1 = n / 10;

                if (temp == 1)

                   count += 1;

                while(temp1>0)

                {

                    int temp2 = temp1 % 10;

                    if (temp2 == 1)

                       count += 1;

                   temp1 = temp1 / 10;

                }

                n--;

            }

            return count;

        }

一道算法题