蚁群算法（ACO）学习笔记
https://blog.csdn.net/fulongxu/article/details/99678958?ops_request_misc=&request_id=&biz_id=102&utm_term=c++%20%E8%9A%81%E7%BE%A4%E7%AE%97%E6%B3%95&utm_medium=distribute.pc_search_result.none-task-blog-2~blog~sobaiduweb~default-5-99678958.nonecase&spm=1018.2226.3001.44501 6734 1453
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#include<bits/stdc++.h>
#define Read() freopen("data.in","r",stdin)
#define Write() freopen("autocomplete.out","w",stdout)
using namespace std;
const int City_Num = 48;//城市数目
const int Ant_Num = 20;//蚂蚁数目
const int Total_Num = 2000;//迭代次数
double Distance;//保存距离
vector<int> Edge;//保存每条边有哪些蚂蚁走过
double Ant_length;//保存每只蚂蚁一轮后走过的路径长度
double Edge_Info;//保存每条边的信息素
vector<int> Ant;//保存每个蚂蚁的路径
int vis;//标记每个蚂蚁走过哪个城市
double Total_Length;//记录每轮迭代后每只蚂蚁走的总路长
vector<int> Min_Path;
double Alpha = 1.0;
double Beta = 5.0;
double Rho = 0.5;
double Min_Length = 0x3f3f3f3f;
struct node
{
int x, y;
}Node;
double Get_distance(node a, node b)
{
return sqrt((1.0*(a.x-b.x)*(a.x-b.x) + 1.0*(a.y-b.y)*(a.y-b.y))/10.0);
}
void Init()
{
for(int i = 0; i < City_Num; i++)
{
Distance = 0;
Edge_Info = 0;
for(int j = i+1; j < City_Num; j++)
{
Distance = Get_distance(Node, Node);
Distance = Distance;
Edge_Info = 0.1;
Edge_Info = 0.1;
}
}
}
int Rand()
{
return rand()%48;
}
double Rand_Double()
{
return (rand()%10000)/10000.0;
}
void Build_Path()
{
for(int i = 0; i < Ant_Num; i++)
{
while(Ant.size() != City_Num)
{
double sum = 0.0;
double p_go;//计算访问下一个城市的概率
memset(p_go, 0, sizeof(p_go));
int total_pos = Ant.size();
int now_pos = Ant;
for(int j = 0; j < City_Num; j++)
{
if(vis) continue;
p_go = pow(Edge_Info, Alpha)*pow((1.0/Distance), Beta);
sum += p_go;
}
double p = Rand_Double();
double p_total = 0;
for(int j = 0; j < City_Num; j++)
{
if(vis) continue;
if(p_total+(p_go/sum) >= p)//下一个访问的城市是j
{
vis = 1;//标记该城市已经走过
Ant.push_back(j);//把这个城市加到城市列表中
Total_Length += Distance;//计算第i只蚂蚁当前一共走的距离
Edge.push_back(i);//记录走过这条边的蚂蚁，用来更新信息素矩阵
break;
}
else
{
p_total += (p_go/sum);
}
}
}
Total_Length += Distance]];//将终点到起点的路长加入到总路长中
Edge]].push_back(i);//终点指向起点的路的蚂蚁记录一下
if(Min_Length > Total_Length)//寻找全局最短路径,并记录路径
{
Min_Length = Total_Length;
Min_Path.clear();
for(int k = 0; k < City_Num; k++)
Min_Path.push_back(Ant);
Min_Path.push_back(Ant);
}
}
}
double Get_Edge_P(int x, int y)
{
int n = Edge.size();
double sum = 0.0;
for(int i = 0; i < n; i++)
{
int ant = Edge;
sum += 1.0/Total_Length;
}
return sum;
}
void Change_Info()
{
for(int i = 0; i < City_Num; i++)
{
for(int j = i+1; j < City_Num; j++)
{
double edge_p = Get_Edge_P(i, j);
Edge_Info = (1.0-Rho)*Edge_Info + edge_p;
Edge_Info = Edge_Info;
}
}
}
void Print()
{
cout<<Min_Length<<endl;
for(int i = 0; i < City_Num; i++)
cout<<Min_Path<<"-->";
cout<<Min_Path<<endl;
}
int main()
{
srand(time(NULL));
Read();
for(int i = 0; i < City_Num; i++)
{
int num, x, y;
cin >>num>>x>>y;
Node.x = x;
Node.y = y;
}
for(int i = 0; i < 48; i++)
cout<<i+1<<" "<<Node.x<<" "<<Node.y<<endl;
cout<<endl<<endl;
Init();
int T = Total_Num;
while(T--)
{
memset(vis, 0, sizeof(vis));
for(int i = 0; i < Ant_Num; i++)
{
Ant.clear();
Total_Length = 0;
}
for(int i = 0; i < Ant_Num; i++)
{
int start_city = Rand();
vis = 1;
Ant.push_back(start_city);
}
Build_Path();//构建路径
Change_Info();//信息素更新
}
Print();//打印最优路径
return 0;
}
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