格雷码生成算法

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格雷码⽣成算法

在博客中看到过⼀次格雷码⽣成算法,我在这⾥也想写⼀下。

原⽂中的算法为:假设已经⽣成了k位格雷码,那么k+1位格雷码的⽣成⽅式为(1) 按序在k位格雷码前插⼊⼀位0,⽣成⼀组编码,(2)按逆序

在k位格雷码前插⼊⼀位1,⽣成另外⼀组编码,两组编码合起来就是k+1位格雷码。

如下例:

已有2位格雷码:00, 01, 11, 10,要⽣成3位格雷码,采⽤此算法:

(1)按序在各码前插⼊0,⽣成000,001, 011,010;

(2)按逆序在各码前插⼊1,⽣成110,111, 101,100;

(3)将两组编码组合起来:000, 001, 011, 010, 110, 111, 101, 100,为3位格雷码。

另外⼀种算法与此算法类似,不同的是插⼊的位是在格雷码的后⾯:

对于k位格雷码,在各格雷码后⾯分别插⼊0, 1 或 1, 0,⽣成两个编码,所有插⼊完成后组合起来的编码为k+1位格雷码。

如已有2位格雷码:00,01,11,10,⽣成3位格雷码,采⽤此算法:

(1)在00编码后⾯分别插⼊0,1,⽣成000, 001;

(2)在01编码后⾯分别插⼊1,0,⽣成011, 010;

(3)在11编码后⾯分别插⼊0,1,⽣成110, 111;

(4)在10编码后⾯分别插⼊1,0,⽣成101,100;

(5)将⽣成的编码组合起来:000, 001, 011, 010, 110, 111, 101, 100,为3位格雷码。

#include

#include

#include

#include

void GrayCodeOne(int num);

void GrayCodeTwo(int num);

using namespace std;

int main()

{

int count;

cout << "Input Code Number:";

cin >> count;

cout << "Produce Gray Code using method 1" << endl;

clock_t beginOne = clock();

GrayCodeOne(count);

clock_t endOne = clock();

cout << "Gray Code First Method using time: " << (endOne - beginOne) << endl;

cout << "Produce Gray Code using method 2" << endl;

clock_t beginTwo = clock();

GrayCodeTwo(count);

clock_t endTwo = clock();

cout << "Gray Code Second Method using time: " << (endTwo - beginTwo) << endl;

return 0;

}

// Method to produce gray code using method inserting 0 in front of old gray code by positive

// and inserting 1 in front of old gray code by nagative.

void GrayCodeOne(int num)

{

if (num < 1)

{

cout << "Error input Integer" << endl;

return;

}

vector codeVec;

int cIdx = 1;

for (; cIdx <= num; cIdx++)

{

if (codeVec.size() < 2)

{

codeVec.push_back("0");

codeVec.push_back("1");

}

else

{

vector tranVec;

tranVec.resize(2 * codeVec.size());

int tranIdx = 0;

vector::iterator codeIter = codeVec.begin();

for (; codeIter != codeVec.end(); codeIter++)

{

string str = "0";

str.append(*codeIter);

tranVec[tranIdx++] = str;

}

vector::reverse_iterator rCodeIter = codeVec.rbegin();

for (; rCodeIter != codeVec.rend(); rCodeIter++)

{

string str = "1";

str.append(*rCodeIter);

tranVec[tranIdx++] = str;

}

codeVec.assign(tranVec.begin(), tranVec.end());

}

}

//vector::iterator vecIter = codeVec.begin();

//for (; vecIter != codeVec.end(); vecIter++)

//{

// cout << *vecIter << endl;

//}

return;

}

// Method to produce gray code using method inserting 0/1 in the back of first gray code

// then inserting 1/0 in the back of next gray code.

void GrayCodeTwo(int num)

{

if (num < 1)

{

cout << "Input error Integer" << endl;

return;

}

vector codeVec;

int cIdx = 1;

for (; cIdx <= num; cIdx++)

{

if (codeVec.size() < 2)

{

codeVec.push_back("0");

codeVec.push_back("1");

}

else

{

vector tranVec;

int tranIdx = 0;

int cIdx = codeVec.size();

tranVec.resize(2 * cIdx);

for (int vIdx = 0; vIdx < cIdx; vIdx++)

{

string str = codeVec[vIdx];

if (0 == (vIdx % 2))

{

string str0 = str;

str0.append("0");

tranVec[tranIdx++] = str0;

string str1 = str; str1.append("1");

tranVec[tranIdx++] = str1;

}

else

{

string str0 = str;

str0.append("1");

tranVec[tranIdx++] = str0;

string str1 = str;

str1.append("0");

tranVec[tranIdx++] = str1;

}

}

codeVec.assign(tranVec.begin(), tranVec.end());

}

}

//vector::iterator vecIter = codeVec.begin();

//for (; vecIter != codeVec.end(); vecIter++)

//{

// cout << *vecIter << endl;

//}

return;

}

运⾏时间的测试:

12位格雷码,⽅法⼀和⽅法⼆所需时钟数

16位格雷码,两种⽅法所需时钟数