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GrayCode.cpp
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GrayCode.cpp
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/*
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.
For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:
00 - 0
01 - 1
11 - 3
10 - 2
Note:
For a given n, a gray code sequence is not uniquely defined.
For example, [0,2,3,1] is also a valid gray code sequence according to the above definition.
For now, the judge is able to judge based on one instance of gray code sequence. Sorry about that.
*/
Solution {
public:
vector<int> grayCode(int n) {
vector<int> result(1<<n,0);
for(int i=0;i<1<<n;i++)
result[i] = (i >> 1) ^ i;
return result;
}
vector<int> grayCode_2(int n)
{
vector<int> result;
result.push_back(0);
int carry = 1;
for(int i=1;i<=n;i++)
{
int len = result.size();
for(int j=len-1;j>=0;j--)
{
int num = result[j]^carry;
result.push_back(num);
}
carry<<=1;
}
return result;
}
}
};