#include <bits/stdc++.h>
#include <sl/debug.h>
struct Seg {
std::vector <long long> v, w;
int size;
Seg(int s) {
size = 1;
while (size < s) {
size <<= 1;
}
v.resize(size << 1, 0);
w.resize(size << 1, 0);
}
void update(int l, int r, long long delta) {
update(l, r, delta, 0, 0, size);
}
void update(int tl, int tr, long long delta, int now, int l, int r) {
if (l >= tr || r <= tl) {
return;
}
if (l >= tl && r <= tr) {
w[now] += delta;
return;
}
push(now, l, r);
int mid = (l + r) >> 1;
update(tl, tr, delta, now * 2 + 1, l, mid);
update(tl, tr, delta, now * 2 + 2, mid, r);
}
long long query(int l, int r) {
return query(l, r, 0, 0, size);
}
long long query(int tl, int tr, int now, int l, int r) {
if (l >= tr || r <= tl) {
return 0;
}
push(now, l, r);
if (l >= tl && r <= tr) {
return v[now];
}
int mid = (l + r) >> 1;
return std::max(query(tl, tr, now * 2 + 1, l, mid), query(tl, tr, now * 2 + 2, mid, r));
}
void push(int node, int l, int r) {
v[node] += w[node] * (r - l);
if (r - l - 1) {
w[node * 2 + 1] += w[node];
w[node * 2 + 2] += w[node];
}
w[node] = 0;
}
};
int n;
std::vector <std::vector <std::pair <int, std::pair <int, int>>>> g;
std::vector <std::vector <int>> c;
std::vector <int> cc;
std::vector <long long> cans;
void fc(int node, std::vector <bool>& vis) {
if (vis[node]) {
return;
}
vis[node] = true;
c.back().push_back(node);
for (auto p : g[node]) {
fc(p.second.first, vis);
}
}
std::vector <bool> cyc;
bool cy(int node, int par, std::vector <bool>& vis) {
if (vis[node]) {
return cyc[node] = true;
}
vis[node] = true;
for (auto p : g[node]) {
if (p.first != par && cy(p.second.first, p.first, vis)) {
return cyc[node] ? false : (cyc[node] = true);
}
}
return false;
}
long long td(int node, int par = -1) {
std::vector <long long> ch;
for (auto p : g[node]) {
if (p.second.first == par || cyc[p.second.first]) {
continue;
}
ch.push_back(td(p.second.first, node) + p.second.second);
}
std::sort(ch.rbegin(), ch.rend());
if (ch.size()) {
cans[cc[node]] =
std::max(cans[cc[node]], (int) ch.size() > 1 ? ch[0] + ch[1] : ch.empty() ? 0LL : ch[0]);
}
return ch.size() ? ch[0] : 0LL;
}
std::vector <long long> sus;
void gse(int node, int par, std::vector <bool>& vis, std::vector <std::pair <long long, long long>>& seq) {
for (auto p : g[node]) {
if (p.second.first != par && cyc[p.second.first] && !vis[p.second.first]) {
vis[p.second.first] = true;
seq.emplace_back(sus[p.second.first], p.second.second);
gse(p.second.first, node, vis, seq);
}
}
}
int main() {
std::ios::sync_with_stdio(0); std::cin.tie(0);
std::cin >> n;
g.resize(n);
for (int i = 0; i < n; i++) {
int u, w; std::cin >> u >> w; u--;
g[u].push_back({ i, { i, w } });
g[i].push_back({ i, { u, w } });
}
std::vector <bool> vis(n, false);
cc.resize(n, -1);
for (int i = 0; i < n; i++) {
if (vis[i]) {
continue;
}
c.resize(c.size() + 1);
cans.resize(cans.size() + 1, 0);
fc(i, vis);
for (int x : c.back()) {
cc[x] = (int) c.size() - 1;
}
}
cyc.resize(n, false);
vis = std::vector <bool> (n, false);
for (auto& v : c) {
cy(v[0], -1, vis);
}
sus.resize(n, 0);
for (int i = 0; i < n; i++) {
if (cyc[i]) {
sus[i] = td(i);
}
}
vis = std::vector <bool> (n, false);
for (int i = 0; i < n; i++) {
if (!vis[i] && cyc[i]) {
std::vector <std::pair <long long, long long>> seq;
gse(i, -1, vis, seq);
if ((int) seq.size() < 2) {
seq.clear();
for (int x : c[cc[i]]) {
if (cyc[x]) {
for (auto p : g[x]) {
if (cyc[p.second.first]) {
seq.emplace_back(sus[p.second.first], p.second.second);
}
}
}
}
std::sort(seq.begin(), seq.end(), [] (
std::pair <long long, long long> u, std::pair <long long, long long> v) {
return u.second < v.second;
});
seq = { seq.front(), seq.back() };
}
int m = seq.size();
//for (int k = 0; k < 2; k++) {
//Seg seg(m);
//long long sum = 0;
//for (int j = 0; j < m; j++) {
//seg.update(j, j + 1, seq[j].first + (sum += seq[j].second));
//}
//for (int j = 0; j < m; j++) {
//seg.update(j + 1, m, -seq[j].second);
//cans[cc[i]] = std::max(cans[cc[j]], seg.query(0, m));
//seg.update(0, m, seq[0].second);
//}
//long long tmp = seq[0].second;
//for (int j = 1; j < m; j++) {
//seq[j - 1].second = seq[j].second;
//}
//seq[m - 1].second = tmp;
//std::reverse(seq.begin(), seq.end());
//}
for (int j = 0; j < m; j++) {
long long sum = seq[j].first;
for (int k = 1; k < m; k++) {
int ind = (j + k) % m;
cans[cc[i]] = std::max(cans[cc[i]], (sum += seq[ind].second) + seq[ind].first);
}
}
}
}
long long ans = 0;
for (long long x : cans) {
ans += x;
}
std::cout << ans << "\n";
}
Compilation message
islands.cpp:3:10: fatal error: sl/debug.h: No such file or directory
3 | #include <sl/debug.h>
| ^~~~~~~~~~~~
compilation terminated.
