格雷码生成 对于给定的正整数n，格雷码为满足如下条件的一个编码序列： (1) 序列由2n个编码组成，每个编码都是长度为n的二进制位串。 (2) 序列中无相同的编码。 (3) 序列中位置相邻的两个编码恰有一位不同。-Gray code are generated for a given positive integer n, the Gray code to meet a coding sequence of the following conditions: (1) sequences encoded by the 2n components, each coding are binary bit string of length n. (2) Sequence in the same encoding. (3) a sequence position adjacent to the two coded exactly one different.