#include "islands.h"
#include<bits/stdc++.h>
using namespace std;
#define in insert
#define all(x) x.begin(),x.end()
#define pb push_back
#define eb emplace_back
#define ff first
#define ss second
//#define int long long
typedef long long ll;
typedef vector<int> vi;
typedef set<int> si;
typedef multiset<int> msi;
typedef pair<int, int> pii;
typedef vector<pii> vpii;
const int mxn = 1e5 + 10;
vector<pair<int, int>> g[mxn];
bool tp, found;
vector<int> ans;
int vis[mxn], p[mxn], rev[mxn];
void dfs(int to, int fr) {
p[to] = fr;
vis[to] = 1;
vector<int> lol;
for(auto it : g[to]) {
int x = it.ff, id = it.ss;
if(id == fr || vis[x]) continue;
lol.pb(id);
}
if(lol.size() >= 2 && !tp) {
vector<int> tmp = ans;
tmp.pb(lol[0]);
tmp.pb(rev[lol[0]]);
tmp.pb(lol[1]);
tmp.pb(rev[lol[1]]);
tmp.pb(rev[lol[0]]);
tmp.pb(lol[0]);
tmp.pb(rev[lol[1]]);
tmp.pb(lol[1]);
tmp.in(tmp.end(), ans.rbegin(), ans.rend());
swap(tmp, ans);
found = 1;
return;
}
if(found) return;
for(auto it : g[to]) {
int x = it.ff, id = it.ss;
if(vis[x] == 2) continue;
if(rev[id] == fr) continue;
ans.pb(id);
if(vis[x] == 1) {
found = 1;
vector<int> cyc;
while(ans.size() && ans.back() != p[x]) {
cyc.pb(ans.back());
ans.pop_back();
}
reverse(all(cyc));
vector<int> tmp = ans;
if(tp) {
for(int x : cyc) tmp.pb(x);
for(int x : cyc) tmp.pb(rev[x]);
reverse(all(cyc));
for(int x : cyc) tmp.pb(x);
for(int x : cyc) tmp.pb(rev[x]);
} else {
for(int x : cyc) tmp.pb(x);
reverse(all(cyc));
for(int x : cyc) tmp.pb(rev[x]);
for(int x : cyc) tmp.pb(x);
reverse(all(cyc));
for(int x : cyc) tmp.pb(rev[x]);
}
tmp.in(tmp.end(), ans.rbegin(), ans.rend());
swap(tmp, ans);
} else {
dfs(x, id);
}
if(found) return;
ans.pop_back();
}
vis[to] = 2;
}
variant<bool, vector<int>> find_journey(int n, int m, vector<int> U, vector<int> V) {
if(n == 2) {
vector<int> a0, a1;
for(int i = 0; i < m; i++) {
if(U[i] == 0) a0.pb(i);
else a1.pb(i);
}
if(a0.size() >= 2 && a1.size() >= 1) return vector<int>{a0[0], a1[0], a0[1], a0[0], a1[0], a0[1]};
else return false;
}
if(U[0] == U[1]) tp = 1;
map<pair<int, int>, int> mp;
for(int i = 0; i < m; i++) {
g[U[i]].eb(V[i], i);
if(mp.find({V[i], U[i]}) != mp.end()) {
int id = mp[{V[i], U[i]}];
rev[id] = i;
rev[i] = id;
}
else if(mp.find({U[i], V[i]}) != mp.end()) {
int id = mp[{U[i], V[i]}];
rev[id] = i;
rev[i] = id;
}
mp[{U[i], V[i]}] = i;
}
dfs(0, -10000);
if(found) return ans;
return false;
}
Compilation message
circuit.cpp:1:10: fatal error: islands.h: No such file or directory
1 | #include "islands.h"
| ^~~~~~~~~~~
compilation terminated.
