局部搜索算法源代码

# include

# include

# include

# include

using namespace std;

#define SAT 3 //每个子句所含变量的个数，即定义N-SAT问题的N

int **arr; //描述SAT问题的二维数组

int Var_Num; //变元个数

int Clause_Num; //子句个数

ifstream fin;

ofstream fout;

void Random(int *v, int *s);

int Proper_Num(int *s);

void Reverse(int *v,int *s, int num);

void Local_Search(double &duration);

void Read_And_Save(int it);

int main()

{

srand(time(NULL));

fout.open("result50-Local_Search_Algorithm.txt");

fout << "#姓名学号" << endl;

double totaltime = 0.0;

for (int i = 1; i <= 10; ++i)

{

double duration=0.0;

Read_And_Save(i);

Local_Search(duration);

totaltime += duration;

}

fout.close();

cout<<"平均时间为： "<< totaltime / 10 <<" 秒 "<

system("pause");

return 0;

}

//随机生成一个真值指派v，并计算在这个真值指派v下每个子句中满足1的数量，可能值从0-3，存于s中

void Random(int *v, int *s)

{

int temp, i, j, k;

for (i = 0; i < Var_Num;i++)

v[i] = rand() % 2;

memset(s, 0, sizeof(int) * Clause_Num);

for (k = 0; k < Var_Num; k++)

for (i = 0; i < Clause_Num; i++)

for (j = 0; j < SAT; j++)

{

temp = (v[k] == 1) ? (k + 1) : -(k + 1);

if (arr[i][j] == temp)

{

++s[i];

break;

}

}

}

//计算符合的子句数，可能值从0-91

int Proper_Num(int *s)

{

int k = 0;

for (int i = 0; i < Clause_Num; i++)

if (s[i] > 0) ++k;

return k;

}

//尝试对第num位进行翻转

void Reverse(int *v,int *s, int num)

{

int i, j, temp;

int preSatify = Proper_Num(s);

int *offset = new int[Clause_Num];

memset(offset, 0, sizeof(int) * Clause_Num);

for (i = 0; i < Clause_Num; i++) //计算翻转后的可满足子句数量的偏移值for (j = 0;j < SAT;j++)

{

temp = (v[num] == 1) ? (num + 1) : -(num + 1);

if (arr[i][j] == temp)

{

offset[i] = offset[i] - 1;

break;

}

if (arr[i][j] == -temp)

{

offset[i] = offset[i] + 1;

break;

}

}

for (i = 0;i < Clause_Num; i++) //修改生成新的可满足子句

s[i] = s[i] + offset[i];

int newSatify = Proper_Num(s); //计算新的可满足子句个数

if (newSatify > preSatify) //满足子句个数增加则翻转

v[num] = 1 - v[num];

else

for (i = 0; i < Clause_Num; i++) //否则复原可满足子句向量

s[i] = s[i] - offset[i];

delete[] offset;

}

//局部搜索思想求解

void Local_Search(double &duration)

{

int i;

int *sentence = new int[Clause_Num];

int *value = new int[Var_Num];

int tries = 0; //尝试次数

int changenum; //翻转位

double start_time = (double)clock();

Random(value, sentence); //随机生成一组真值指派

while (Proper_Num(sentence) < Clause_Num) //当未使91个子句都满足时...

{

if (tries >= Var_Num * 10) //若尝试次数大于变元数的10倍

{

Random(value, sentence);

tries = 0;

}

changenum = rand() % Var_Num; //随机选一个翻转位

Reverse(value, sentence, changenum); //尝试翻转

++tries;

}

double end_time = (double)clock();

duration =(end_time-start_time)/1000;

fout << "-" << SAT << "-" << Var_Num << "-" << Clause_Num << "-" << duration << endl;

for (i = 0; i < Var_Num; ++i)

fout << value[i];

fout << endl;

for (i = 0; i < Clause_Num;i++)

delete[] arr[i];

delete[] sentence;

delete[] arr;

}

//读取文件并把问题各子句的描述存进二维数组arr

void Read_And_Save(int it)

{

string s;

int i, j, nn;

char sc[20];

fout << "#t" << it << ".txt ";

itoa(it, sc, 10);

string infn = "test\\t" + (string)sc;

infn += ".txt";

fin.open(infn.c_str());

do

fin >> s;

while(s != "cnf");

fin >> Var_Num;

fin >> Clause_Num;

arr = new int*[Clause_Num];

for (i = 0; i < Clause_Num; i++)

{

arr[i] = new int[SAT];

for (j = 0; j < SAT; j++)

fin >> arr[i][j];

fin >> nn;

}

fin.close();

}