The gray code is a binary numeral system where two successive values differ in only one bit.
Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0.
Example 1:
Input: 2
Output: [0,1,3,2]
Explanation:
00 - 0
01 - 1
11 - 3
10 - 2
For a given n, a gray code sequence may not be uniquely defined.
For example, [0,2,3,1] is also a valid gray code sequence.
00 - 0
10 - 2
11 - 3
01 - 1
Example 2:
Input: 0
Output: [0]
Explanation: We define the gray code sequence to begin with 0.
A gray code sequence of n has size = 2n, which for n = 0 the size is 20 = 1.
Therefore, for n = 0 the gray code sequence is [0].
AC代码
class Solution {
public:
vector<int> grayCode(int n) {
int size = pow(2, n);
vector<int> res(size);
for (int i = 0; i < n; ++i) {
int base = pow(2, i);
for (int j = base, k = 1; j < pow(2, i + 1); j++, k += 2)
res[j] = base + res[j - k];
}
return res;
}
};
总结
找规律题目，文字不好解释，画个图吧
