# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
587965 | MrDeboo | Dreaming (IOI13_dreaming) | C++17 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
vector<pair<int,int>>vct[100000];
vector<pair<int,int>>vec[100000];
int fath[100000];
int val[100000];
int n,m,l,f,ans;
int diam(int in){
deque<pair<int,int>>dq={{in,0}};
map<int,bool>vis;
vis[in]=1;
int x=0,y=0;
while(dq.size()){
int a=dq.front().first,b=dq.front().second;
dq.pop_front();
if(b>=y){
x=a;
y=b;
}
for(auto &i:vct[a]){
if(!vis[i.first]){
vis[i.first]=1;
dq.push_back({i.first,b+i.second});
}
}
}
dq.push_back({x,0});
x=0;y=0;
vis.clear();
vis[dq.back().first]=1;
while(dq.size()){
int a=dq.front().first,b=dq.front().second;
dq.pop_front();
if(b>=y){
x=a;
y=b;
}
for(auto &i:vct[a]){
if(!vis[i.first]){
vis[i.first]=1;
dq.push_back({i.first,b+i.second});
}
}
}
return y;
}
int dfs1(int in){
for(auto &i:vec[in])val[in]=max(val[in],dfs1(i.first)+i.second);
return val[in];
}
void dfs2(int in,int x){
f=min(f,max(x,val[in]));
for(auto &i:vec[in])dfs2(i.first,x+i.second);
}
int travelTime(int N, int M, int L, int a[], int b[], int t[]){
n=N,m=M,l=L;
for(int i=0;i<m;i++){
vct[a[i]].push_back({b[i],t[i]});
vct[b[i]].push_back({a[i],t[i]});
}
vector<int>vis(n);
deque<int>v;
for(int i=0;i<n;i++){
if(vis[i])continue;
vis[i]=1;
vector<int>vc={i};
{
deque<int>dq={i};
while(dq.size()){
int a=dq.front();
dq.pop_front();
for(auto &w:vct[a]){
if(!vis[w.first]){
vis[w.first]=1;
vec[a].push_back(w);
fath[w.first]=a;
dq.push_back(w.first);
vc.push_back(w.first);
}
}
}
}
f=INT_MAX;
ans=max(ans,diam(i));
if(vc.size()==1)f=0;
else{
dfs1(i);
f=min(f,val[i]);
vector<pair<int,int>>V={{0,-1}};
for(auto &w:vec[i])V.push_back({w.second+val[w.first],w.first});
sort(V.begin(),V.end());
for(auto &w:vec[i]){
if(w.first==V.back().second)dfs2(w.first,V[V.size()-2].first+w.second);
else dfs2(w.first,V.back().first+w.second);
}
}
v.push_back(f);
}
sort(v.begin(),v.end());
if(v.size()>2)ans=max(ans,min(v[v.size()-2]+v[v.size()-3]+l*2,v[v.size()-2]+l+v.back()));
else(v.size()>1)ans=max(ans,v[v.size()-2]+l+v.back());
return ans;
}