TSP 之模拟退火算法 cpp实现

参数太难调了，很多情况下效果都不好，

 

完整程序下载

 

 

/*simulated annealing algorithm for TSP * @author: [e-mail] */#include <iostream>#include <fstream>#include <vector>#include <algorithm>#include <stdlib.h>#include <time.h>#include <assert.h>#include <math.h>using namespace std;//calculate length of a pathdouble calc_path_len(vector<int> path,vector<vector<double> >& distance){double dis=0;for (int i=0;i<path.size()-1;i++){dis+=distance[path[i]][path[i+1]];}dis+=distance[path[path.size()-1]][path[0]];return dis;}//generate a integer sequence from 0 to n-1 at randomvoid rand_int_order(vector<int>& randorder,const int n) { assert(n>1); randorder.clear();randorder.resize(n);vector<int> recoder;for (int i=0;i<n;i++){recoder.push_back(i);}for(int i=0;i<n;i++){int sel=rand()%recoder.size();randorder[i]=recoder[sel];recoder.erase(recoder.begin()+sel);}assert(randorder.size()==n);}int main(){srand((unsigned)time(NULL));//read data from filefstream filein("data/berlin52.tsp.processed",ios::in);if (filein==NULL){cout<<"cannot open data file"<<endl;return 1;}fstream fileout("data/result.txt",ios::out);if (fileout==NULL){cout<<"cannot open a file to write data"<<endl;return 1;}//append the best result found in this test to a file named "best.txt"fstream bestout("data/best.txt",ios::app);if (bestout==NULL){cout<<"cannot open a file to write data"<<endl;return 1;}//number of citiesunsigned int cityNum;filein>>cityNum;cout<<cityNum<<endl;//standard pathint* standardPath;standardPath=new int[cityNum];for (int i=0;i<cityNum;i++){filein>>standardPath[i];}//distance between citiesvector<vector<double> > distance;for (int i=0;i<cityNum;i++){vector<double> v;for (int j=0;j<cityNum;j++){double d;filein>>d;v.push_back(d);}distance.push_back(v);}////////////////////////////////////////////////////////////////////////////parameters//initial temperaturedouble T_start;//final temperaturedouble T_final=1;//time of circulation at a certain temperatureint L=10000;//ratio of temperature reductiondouble alpha=0.95;//initial pathvector<int> path;//initialization rand_int_order(path,cityNum);//length of best path founddouble best_path_len=1<<(8*sizeof(int)-2);//initialize T-start=K*disDelta;K(10,20,100... ),disDelta=max(distance)-min(distance).double max_dist=0;double min_dist=best_path_len;for (int i=0;i<cityNum;i++){for (int j=0;j<cityNum&&i>j;j++){if (max_dist<distance[i][j]){max_dist=distance[i][j];}if (min_dist>distance[i][j]){min_dist=distance[i][j];}}}for (int temperature=1;temperature<2;temperature++){//test initial temperature//assign initial temperatureT_start=(max_dist-min_dist)*temperature*50;double T=T_start;//annealingwhile(T>T_final){for(int l=0;l<L;l++){int point_former=rand()%(cityNum-2);int point_latter=point_former;while(point_former==point_latter){point_latter=rand()%(cityNum-1);}//make sure point_former is smaller than point_latterif (point_former>point_latter){int t=point_latter;point_latter=point_former;point_former=t;}////new pathvector<int> newPath=path;//2-opt//reverse(newPath.begin()+point_former,newPath.begin()+point_latter);//3-optint point_c=point_latter;while(point_c<=point_latter){point_c=rand()%cityNum;}vector<int>tmp(newPath.begin()+point_former,newPath.begin()+point_latter);newPath.insert(newPath.begin()+point_c,tmp.begin(),tmp.end());newPath.erase(newPath.begin()+point_former,newPath.begin()+point_latter);double newLen=calc_path_len(newPath,distance);double delta_dist=newLen-best_path_len;//acceptance criteriaif (delta_dist<0||exp(-delta_dist/T)>rand()/RAND_MAX){best_path_len=newLen;fileout<<"best distance found for the moment: "<<best_path_len<<endl<<"path found for the moment:"<<endl;for (int i=0;i<cityNum;i++){fileout<<path[i]<<" ";}fileout<<endl;//to consolecout<<"best distance found for the moment: "<<best_path_len<<endl<<"best path found for the moment:"<<endl;for (int i=0;i<cityNum;i++){cout<<path[i]<<" ";}cout<<endl;//jump out cycle of this temperaturebreak;}}//reduce temperatureT*=alpha;}bestout<<"current temperature: "<<10*temperature*(max_dist-min_dist)<<endl;bestout<<best_path_len<<endl;for (int i=0;i<cityNum;i++){bestout<<path[i]<<" ";}bestout<<endl;//record timetime_t currenttime;time(¤ttime);bestout<<ctime(¤ttime);}//show standard path and distancefileout<<"standard path:"<<endl;double standardbestlen=0;for (int i=0;i<cityNum;i++){fileout<<standardPath[i]<<" ";}for (int i=0;i<cityNum-1;i++){standardbestlen+=distance[standardPath[i]][standardPath[i+1]];}standardbestlen+=distance[standardPath[cityNum-1]][standardPath[0]];fileout<<endl<<"length of standard path: "<<endl<<""<<standardbestlen<<endl;//free memory/////////////////////////////////////////////////////////////filein.close();fileout.close();bestout.close();delete[] standardPath;return 0;}