#include<bits/stdc++.h>
//#include "citymapping.h"
using namespace std;
#define all(fl) fl.begin(),fl.end()
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=j;i<=k;i++)
#define for2(i,j,k) for(int i=j;i>=k;i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pli pair<long long,int>
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
#define pil pair<int,long long>
vector<pii>aaa[1009];
mt19937_64 rng(101094);
vector<int>cc[1009];
int f[1009];
long long d[1009][1009];
long long ask(int x,int y){
if (d[x][y]!=-1)return d[x][y];
return d[x][y]=d[y][x]=get_distance(x,y);
}
int fs(int u){
if (f[u]<0)return u;
return f[u]=fs(f[u]);
}
void unite(int u,int v,int w){
int u1=u,v1=v;
u=fs(u),v=fs(v);
if (u==v)return;
if (f[u]>f[v]){
swap(u,v);
swap(u1,v1);
}
f[u]+=f[v];
for (auto vx:cc[u]){
for (auto vy:cc[v]){
d[vx][vy]=d[vy][vx]=1ll*w+d[vx][u1]+d[vy][v1];
}
}
for (auto vx:cc[v]){
cc[u].pb(vx);
}
cc[v].clear();
}
bool add[1009];
vector<int>xd[1009];
void solve(vector<int>&tmp,int s,int t){
if (sz(tmp)<=1)return;
for (auto v:tmp)add[v]=0;
shuffle(all(tmp),rng);
s=tmp[0],t;
sort(all(tmp),[&](int i,int j){
return ask(s,i)<ask(s,j);
});
t=tmp.back();
vector<int>vertice;
for (auto v:tmp){
if (ask(s,v)+ask(t,v)==ask(s,t)){
vertice.pb(v);
add[v]=1;
}
}
sort(all(vertice),[&](int i,int j){
return ask(s,i)<ask(s,j);
});
auto add_edg=[&](int u,int v,int w){
aaa[u].pb({v,w});
aaa[v].pb({u,w});
d[u][v]=d[v][u]=w;
unite(u,v,w);
//cerr<<u<<" "<<v<<" "<<w<<'\n';
return;
};
for1(i,1,sz(vertice)-1){
add_edg(vertice[i],vertice[i-1],ask(vertice[i],s)-ask(vertice[i-1],s));
}
for(auto v:tmp){
if (add[v])continue;
for (auto u:vertice){
if (ask(s,v)-ask(s,u)==ask(t,v)-ask(t,u)&&ask(s,v)>ask(s,u)){
xd[u].pb(v);
}
}
}
for (auto u:vertice){
if (!xd[u].empty()){
sort(all(xd[u]),[&](int i,int j){
return ask(i,s)<ask(j,s);
});
for (auto v:xd[u]){
d[u][v]=d[v][u]=ask(v,s)-ask(u,s);
}
if (u!=s&&u!=t){
int news=xd[u][0],newt=xd[u].back();
add_edg(u,xd[u][0],d[u][xd[u][0]]);
for (auto v:xd[u]){
d[v][xd[u][0]]=d[xd[u][0]][v]=d[u][v]-d[u][xd[u][0]];
}
vector<int>cop;
cop.swap(xd[u]);
solve(cop,news,newt);
}
else {
vector<int>cop;
int news=u,newt=xd[u].back();
cop.swap(xd[u]);
cop.pb(u);
solve(cop,news,newt);
}
}
}
}
void find_roads(int N, int Q, int A[], int B[], int W[]) {
for1(i,1,N){
f[i]=-1;
cc[i].pb(i);
for1(j,1,N){
d[i][j]=-1;
}
d[i][i]=0;
}
vector<int>tree;
for1(i,1,N)tree.pb(i);
int s=rng()%N+1,t;
while (true){
t=rng()%N+1;
if (s==t)continue;
break;
}
solve(tree,s,t);
int cnt=0;
for1(i,1,N){
for (auto v:aaa[i]){
if (v.fi>i){
A[cnt]=v.fi,B[cnt]=i,W[cnt]=v.se;
cnt++;
}
}
}
}
Compilation message
citymapping.cpp: In function 'long long int ask(int, int)':
citymapping.cpp:26:24: error: 'get_distance' was not declared in this scope
26 | return d[x][y]=d[y][x]=get_distance(x,y);
| ^~~~~~~~~~~~
citymapping.cpp: In function 'void solve(std::vector<int>&, int, int)':
citymapping.cpp:57:11: warning: right operand of comma operator has no effect [-Wunused-value]
57 | s=tmp[0],t;
| ^
