There is a infinite series, whose general term is expressed as: a [n] = 10* 10*....

代码说明：

有一个无穷数列，其通项表示为： a[n]=10*10*... n=0,1,2,3..... 构成了1,10,100,1000... 把它连起来，就成了数串。 判断数串的第i位到底是0还是1.性能要求1s -There is a infinite series, whose general term is expressed as: a [n] = 10* 10*... n = 0,1,2,3 ..... constitute 1,10100,1000 it even ... together, it becomes the number of strings. Determine the number of strings in the end of the first i-bit is 0 or 1. Performance requirements 1s