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tsp.cpp
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tsp.cpp
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#include <vector>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <queue>
#include <iostream>
#include "Vector.hpp"
#include "util.hpp"
using namespace std;
extern vector<Vec2> pos;
extern vector<vector<int> > conn;
extern vector<int> itemID;
extern int startI, endI;
typedef vector<int> ivec;
vector<vector<vector<int> > > itemPath;
vector<vector<int> > startPath, endPath;
namespace {
vector<vector<double> > itemDist;
vector<double> startDist, endDist;
double pathCost(const ivec& v)
{
double r = startDist[v[0]] + endDist[v.back()];
for(size_t i=1; i<v.size(); ++i)
r += itemDist[v[i-1]][v[i]];
return r;
}
double randf()
{
return rand()/(double)RAND_MAX;
}
vector<int> rItemID;
vector<bool> used;
vector<int> from;
void genShortestPaths(int sn, vector<double>& dists, vector<ivec>& paths)
{
int s = itemID[sn];
used.resize(0);
used.resize(conn.size(),0);
from.resize(conn.size());
typedef pair<int,int> IP;
typedef pair<double,IP> P;
priority_queue<P,vector<P>,greater<P> > q;
q.push(P(0,IP(s,-1)));
while(!q.empty()) {
P p = q.top();
q.pop();
double d=p.first;
int n=p.second.first;
int f=p.second.second;
if (used[n]) continue;
used[n]=1;
from[n]=f;
if (rItemID[n]>=0 || n==startI || n==endI) {
ivec& path = n==startI ? startPath[sn] : n==endI ? endPath[sn] : paths[rItemID[n]];
int nn = n;
do {
// cout<<"lol "<<sn<<' '<<n<<' '<<rItemID[n]<<' '<<nn<<'\n';
path.push_back(nn);
} while((nn = from[nn])>=0);
if (n!=startI) reverse(path.begin(),path.end());
// if (n==startI) cout<<"found start path for "<<sn<<" : "<<path<<'\n';
if (n==startI) startDist[sn]=d;
else if (n==endI) endDist[sn]=d;
else dists[rItemID[n]] = d;
}
for(size_t i=0; i<conn[n].size(); ++i) {
int x=conn[n][i];
if (used[x]) continue;
q.push(P(d+length(pos[x]-pos[n]), IP(x,n)));
}
}
}
}
ivec TSP(const ivec& purchases)
{
if (purchases.size()<2) return ivec(purchases);
ivec cur = purchases;
ivec best = cur;
double bdist = pathCost(cur);
double cdist = bdist;
for(double t=10; t>.1; t*=.999) {
size_t a = rand()%(cur.size()-1);
size_t b = rand()%(cur.size()-1);
if (b>=a) ++b;
else swap(a,b);
int ca=cur[a], cb=cur[b];
double da = a ? itemDist[cur[a-1]][cb] - itemDist[cur[a-1]][ca] : startDist[cb] - startDist[ca];
double db = b<cur.size()-1 ? itemDist[ca][cur[b+1]] - itemDist[cb][cur[b+1]] : endDist[ca] - endDist[cb];
double d = da+db;
if (d<0 || randf()<exp(-d/t)) {
reverse(cur.begin()+a,cur.begin()+b+1);
cdist = pathCost(cur);
if (cdist < bdist) {
best = cur;
bdist = cdist;
}
}
}
return best;
}
void initTSP()
{
rItemID.resize(pos.size(), -1);
for(size_t i=0; i<itemID.size(); ++i)
rItemID[itemID[i]] = i;
itemDist.resize(itemID.size());
itemPath.resize(itemID.size());
startDist.resize(itemID.size());
startPath.resize(itemID.size());
endDist.resize(itemID.size());
endPath.resize(itemID.size());
for(size_t i=0; i<itemDist.size(); ++i) {
itemDist[i].resize(itemDist.size());
itemPath[i].resize(itemDist.size());
genShortestPaths(i, itemDist[i], itemPath[i]);
}
}