#include <bits/stdc++.h>
#define f first
#define s second.first
#define tr second.second
#define mp make_pair
using namespace std;
ofstream out("output.txt");
const int MAXN =1e6+1;
typedef long long ll;
int read(){
int r=0;
char ch=getchar();
while(ch<'0'||ch>'9')ch=getchar();
r=ch-'0';
ch=getchar();
while(ch>='0'&&ch<='9'){
r=r*10+ch-'0';
ch=getchar();
}
return r;
}
vector<pair<int,pair<ll,int> > > grafo[MAXN];
ll m[MAXN][4];
deque<int> cyc;
ll succ[MAXN];
bitset<MAXN> v;
bitset<MAXN> k;
ll zipp[MAXN];
int pos[MAXN];
bool find_cyc(int n, int pa){
v[n]=1;
k[n]=1;
cyc.push_back(n);
for(auto x:grafo[n]){
if(!v[x.f]){
if(find_cyc(x.f,x.tr))return true;
}
else if(x.tr!=pa){
cyc.push_back(x.f);
return true;
}
}
cyc.pop_back();
return false;
}
ll zip(int n, int a, int b, int c){
k[n]=1;
ll mas=0;
for(auto x:grafo[n]){
if(x.f==a||x.f==b||x.f==c)continue;
mas=max(mas,zip(x.f,n,b,c)+x.s);
}
return mas;
}
ll dfs(int n, int a){
ll mas=0;
pos[n]=-1;
k[n]=1;
for(auto x:grafo[n]){
if(n==cyc.front()&&x.f==cyc.back())continue;
if(x.f==cyc.front()&&n==cyc.back())continue;
if(x.f==a)continue;
ll p=dfs(x.f,n)+x.s;
if(mas<p){
mas=p;
pos[n]=pos[x.f];
}
}
if(pos[n]==-1)pos[n]=n;
return mas;
}
ll dfs2(int n, int a, int w){
ll mas=0;
pos[n]=-1;
k[n]=1;
for(auto x:grafo[n]){
if(n==cyc.front()&&x.f==cyc.back()&&x.s!=w)continue;
if(x.f==cyc.front()&&n==cyc.back()&&x.s!=w)continue;
if(x.f==a)continue;
ll p=dfs2(x.f,n,w)+x.s;
if(mas<p){
mas=p;
pos[n]=pos[x.f];
}
}
if(pos[n]==-1)pos[n]=n;
return mas;
}
int N;
ll process(int t){
cyc.clear();
find_cyc(t,-1);
while(cyc.front()!=cyc.back())cyc.pop_front();
cyc.pop_front();
zipp[cyc[0]]=zip(cyc[0],-1,cyc[1],cyc.back());
for(int i=1;i<cyc.size()-1;i++)zipp[cyc[i]]=zip(cyc[i],-1,cyc[i-1],cyc[i+1]);
zipp[cyc.back()]=zip(cyc.back(),-1,cyc[cyc.size()-2],cyc.front());
if(cyc.size()==2){
ll mass=0;
for(auto x:grafo[cyc[0]])
if(x.f==cyc[1]){
mass=max(mass,x.s);
}
dfs2(t,-1,mass);
return dfs2(pos[t],-1,mass);
}
for(int i=1;i<cyc.size()-1;i++)
for(auto x:grafo[cyc[i]])
if(x.f==cyc[i+1]){
succ[cyc[i]]=x.s;
break;
}
ll speciale=0;
for(auto x:grafo[cyc[0]]){
if(x.f==cyc[1])succ[cyc[0]]=x.s;
if(x.f==cyc.back())speciale=x.s;
}
int se=cyc.size();
m[cyc[0]][0]=0;
for(int i=1;i<se;i++)m[cyc[i]][0]=m[cyc[i-1]][0]+succ[cyc[i-1]];
m[cyc[0]][1]=zipp[cyc[0]];
for(int i=1;i<se;i++)m[cyc[i]][1]=max(m[cyc[i-1]][1],m[cyc[i]][0]+zipp[cyc[i]]);
m[cyc.back()][2]=0;
for(int i=se-2;i>=0;i--)m[cyc[i]][2]=m[cyc[i+1]][2]+succ[cyc[i]];
m[cyc.back()][3]=zipp[cyc.back()];
for(int i=se-2;i>=0;i--)m[cyc[i]][3]=max(m[cyc[i+1]][3],m[cyc[i]][2]+zipp[cyc[i]]);
ll ans=0;
for(int i=0;i<se-1;i++)ans=max(ans,m[cyc[i]][1]+m[cyc[i+1]][3]+speciale);
dfs(t,-1);
ans=max(ans,dfs(pos[t],-1));
return ans;
}
int main(){
freopen("input.txt","r",stdin);
N=read();
for(int i=0;i<N;i++){
int a,c;
a=read(),c=read();
a--;
grafo[a].push_back(mp(i,mp((ll)c,i)));
grafo[i].push_back(mp(a,mp((ll)c,i)));
}
ll ans=0;
for(int i=0;i<N;i++)
if(!k[i])ans+=process(i);
out<<ans;
}
Compilation message
islands.cpp: In function 'll process(int)':
islands.cpp:102:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=1;i<cyc.size()-1;i++)zipp[cyc[i]]=zip(cyc[i],-1,cyc[i-1],cyc[i+1]);
~^~~~~~~~~~~~~
islands.cpp:113:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=1;i<cyc.size()-1;i++)
~^~~~~~~~~~~~~
islands.cpp: In function 'int main()':
islands.cpp:141:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen("input.txt","r",stdin);
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2087 ms |
23800 KB |
Time limit exceeded |
| 2 |
Execution timed out |
2088 ms |
23800 KB |
Time limit exceeded |
| 3 |
Execution timed out |
2073 ms |
23800 KB |
Time limit exceeded |
| 4 |
Execution timed out |
2086 ms |
23928 KB |
Time limit exceeded |
| 5 |
Execution timed out |
2092 ms |
23800 KB |
Time limit exceeded |
| 6 |
Execution timed out |
2079 ms |
23800 KB |
Time limit exceeded |
| 7 |
Execution timed out |
2083 ms |
23800 KB |
Time limit exceeded |
| 8 |
Execution timed out |
2086 ms |
23800 KB |
Time limit exceeded |
| 9 |
Execution timed out |
2091 ms |
23800 KB |
Time limit exceeded |
| 10 |
Execution timed out |
2096 ms |
23800 KB |
Time limit exceeded |
| 11 |
Execution timed out |
2091 ms |
23804 KB |
Time limit exceeded |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2095 ms |
23800 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2083 ms |
23800 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2089 ms |
23928 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2087 ms |
23800 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2091 ms |
23928 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2082 ms |
23800 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2091 ms |
23800 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Execution timed out |
2088 ms |
23928 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
