题目链接
DFS代码（90分）
#include<iostream>
#include<cmath>
#include<climits>
#include<algorithm>
#include<cstdio>
using namespace std;
int n;
double dx[20],dy[20];
double map[20][20];
int vis[20];
double ans=INT_MAX;
void dfs(int pos,double dis,int step)
{
if(dis>ans)
return ;
if(step==n)
{
ans=min(ans,dis);
return ;
}
vis[pos]=1;
for(int i=1;i<=n;i++)
{
if(vis[i]!=1)
{
vis[i]++;
dfs(i,dis+map[i][pos],step+1);
vis[i]--;
}
}
}
int main()
{
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>dx[i]>>dy[i];
}
for(int x=0;x<=n;x++)
{
for(int y=0;y<=n;y++)
{
map[x][y]=sqrt((dx[x]-dx[y])*(dx[x]-dx[y])+(dy[x]-dy[y])*(dy[x]-dy[y]));
}
}
dfs(0,0,0);
printf("%.2lf",ans);
}
模拟退火代码
#include<iostream>
#include<time.h>
#include<cmath>
#include<cstdio>
#include<algorithm>
using namespace std;
double T0=1e5,Te=1e-6;
double D=0.997;
int L=40;
int n;
double x[25],y[25];
double ans=1e9;
int pos[25];
int st=clock();
double dis(int a,int b)
{
return sqrt((x[a]-x[b])*(x[a]-x[b])+(y[a]-y[b])*(y[a]-y[b]));
}
double cal()
{
double res=0;
for(int i=1;i<=n;i++)
{
res+=dis(pos[i-1],pos[i]);
}
return res;
}
double rand_f() {
return double(rand())/double(RAND_MAX);}
void SA()
{
for(int i=1;i<=n;i++)
{
pos[i]=i;
}
double sum=cal();
double T=T0;
while(T>Te)
{
for(int i=0;i<L;i++)
{
int u=rand()%n+1;
int v=rand()%n+1;
swap(pos[u],pos[v]);
double New_sum=cal();
if(New_sum<sum||exp((sum-New_sum)/T)>rand_f())
{
sum=New_sum;
ans=min(ans,sum);
}
else
{
swap(pos[u],pos[v]);
}
}
T*=D;
}
}
int main()
{
srand(time(0));
scanf("%d",&n);
for(int i=1;i<=n;i++)
{
scanf("%lf%lf",&x[i],&y[i]);
}
while(clock()-st<0.9*CLOCKS_PER_SEC)SA();
printf("%.2lf",ans);return 0;
}