#include <bits/stdc++.h>
using namespace std;
int N;
vector<pair<int, int>> adj[1000005];
bitset<1000005> visited;
bitset<1000005> cycle;
pair<int, int> parent[1000005];
int cyc, cyc2;
int cycval;
long long far[1000005];
long long dp[1000005];
vector<int> chd[1000005];
struct maxheap
{
priority_queue<long long> pq;
priority_queue<long long> del;
void push(const long long &v)
{
pq.push(v);
while(!del.empty() && del.top() == pq.top()) {
pq.pop();
del.pop();
}
}
void dsp(const long long &v)
{
del.push(v);
while(!del.empty() && del.top() == pq.top()) {
pq.pop();
del.pop();
}
}
long long top()
{
return pq.top();
}
void pop()
{
pq.pop();
while(!del.empty() && del.top() == pq.top()) {
pq.pop();
del.pop();
}
}
int Size()
{
return pq.size() - del.size();
}
bool isEmpty()
{
return Size() == 0;
}
void reset()
{
while(!pq.empty()) pq.pop();
while(!del.empty()) del.pop();
}
};
void dfs(const int &v, const int &p, const int &asg)
{
visited[v] = true;
parent[v] = make_pair(p, asg);
int cnt = 0;
int tmp;
for(auto &i:adj[v]){
if(i.first==p){
++cnt;
if(cnt==1) tmp = i.second;
else{
if(cyc == -1){
cyc = v;
cyc2 = i.first;
cycle[v] = true;
cycval = (tmp == asg) ? i.second : tmp;
}
}
continue;
}
if(visited[i.first]){
if(cyc == -1){
cyc = v;
cyc2 = i.first;
cycval = i.second;
cycle[v] = true;
}
continue;
}
dfs(i.first, v, i.second);
}
}
void treedfs(const int &v, const int &prv, const int &p)
{
chd[p].push_back(v);
for(auto &i:adj[v]){
if(i.first == prv || cycle[i.first]) continue;
dp[i.first] = dp[v] + i.second;
treedfs(i.first, v, p);
}
}
void treedfs2(const int &v, const int &prv, const int &p)
{
for(auto &i:adj[v]){
if(cycle[i.first] && i.first != p) continue;
if(i.first == prv) continue;
dp[i.first] = dp[v] + i.second;
treedfs2(i.first, v, p);
}
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0);
long long ans = 0;
cin>>N;
int tmp, k;
for(int i=1;i<=N;i++){
cin>>tmp>>k;
adj[tmp].push_back(make_pair(i, k));
adj[i].push_back(make_pair(tmp, k));
}
for(int i=0;i<1000005;i++) adj[i].shrink_to_fit();
int cycstart, cycend, tt;
long long cur, dsp, sub;
long long m; int loc;
vector<int> fun, val;
for(int i=1;i<=N;i++){
if(visited[i]) continue;
long long tmpans = 0;
vector<int>().swap(fun);
vector<int>().swap(val);
cyc = -1;
cyc2 = -1;
dfs(i, 0, 0);
cycstart = cyc;
cycend = cyc2;
fun.push_back(cycstart);
val.push_back(cycval);
while(cycstart != cycend){
tt = parent[cycstart].second;
cycstart = parent[cycstart].first;
cycle[cycstart] = true;
fun.push_back(cycstart);
val.push_back(tt);
}
fun.shrink_to_fit();
val.shrink_to_fit();
for(int i:fun){
treedfs(i, i, i);
m = -1;
for(int k:chd[i]){
if(dp[k] > m){
m = dp[k];
loc = k;
}
}
far[i] = m;
dp[loc] = 0;
treedfs2(loc, loc, i);
m = -1;
for(int k:chd[i]) m = max(m, dp[k]);
tmpans = max(tmpans, m);
}
maxheap heap;
cur = dsp = sub = 0;
for(int i=1;i<(int)fun.size();i++){
cur += val[i];
heap.push(cur+far[fun[i]]);
}
tmpans = max(tmpans, heap.top()+far[fun[0]]);
for(int i=1;i<(int)fun.size();i++){
dsp += val[i];
heap.dsp(dsp + far[fun[i]]);
sub += val[i];
cur += val[i-1];
heap.push(cur+far[fun[i-1]]);
tmpans = max(tmpans, heap.top()+far[fun[i]]-sub);
}
heap.reset();
cur = dsp = sub = 0;
for(int i=(int)fun.size()-2;i>=0;i--){
cur += val[i+1];
heap.push(cur+far[fun[i]]);
}
tmpans = max(tmpans, heap.top()+far[fun.back()]);
for(int i=(int)fun.size()-2;i>=0;i--){
sub += val[i+1];
dsp += val[i+1];
cur += val[(i+2)%val.size()];
heap.dsp(dsp+far[fun[i]]);
heap.push(cur+far[fun[(i+1)%fun.size()]]);
tmpans = max(tmpans, heap.top() + far[fun[i]]-sub);
}
ans += tmpans;
}
cout<<ans<<'\n';
}
Compilation message
islands.cpp: In function 'void dfs(const int&, const int&, const int&)':
islands.cpp:76:28: warning: 'tmp' may be used uninitialized in this function [-Wmaybe-uninitialized]
76 | cycval = (tmp == asg) ? i.second : tmp;
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
25 ms |
47316 KB |
Output is correct |
| 2 |
Correct |
25 ms |
47336 KB |
Output is correct |
| 3 |
Correct |
29 ms |
47320 KB |
Output is correct |
| 4 |
Correct |
27 ms |
47284 KB |
Output is correct |
| 5 |
Correct |
31 ms |
47284 KB |
Output is correct |
| 6 |
Correct |
28 ms |
47224 KB |
Output is correct |
| 7 |
Correct |
28 ms |
47240 KB |
Output is correct |
| 8 |
Correct |
24 ms |
47272 KB |
Output is correct |
| 9 |
Correct |
28 ms |
47276 KB |
Output is correct |
| 10 |
Correct |
26 ms |
47264 KB |
Output is correct |
| 11 |
Correct |
26 ms |
47328 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
33 ms |
47432 KB |
Output is correct |
| 2 |
Correct |
26 ms |
47444 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
26 ms |
47356 KB |
Output is correct |
| 2 |
Correct |
28 ms |
47760 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
41 ms |
48680 KB |
Output is correct |
| 2 |
Correct |
49 ms |
51572 KB |
Output is correct |
| 3 |
Correct |
35 ms |
48852 KB |
Output is correct |
| 4 |
Correct |
30 ms |
47976 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
63 ms |
53376 KB |
Output is correct |
| 2 |
Correct |
87 ms |
56788 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
120 ms |
62868 KB |
Output is correct |
| 2 |
Correct |
167 ms |
74004 KB |
Output is correct |
| 3 |
Correct |
216 ms |
86040 KB |
Output is correct |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
227 ms |
78540 KB |
Output is correct |
| 2 |
Correct |
284 ms |
108172 KB |
Output is correct |
| 3 |
Correct |
434 ms |
126864 KB |
Output is correct |
| 4 |
Runtime error |
288 ms |
131072 KB |
Execution killed with signal 9 |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
291 ms |
110112 KB |
Output is correct |
| 2 |
Runtime error |
499 ms |
131072 KB |
Execution killed with signal 9 |
| 3 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
298 ms |
131072 KB |
Execution killed with signal 9 |
| 2 |
Halted |
0 ms |
0 KB |
- |
