# | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
---|---|---|---|---|---|---|---|
1184008 | kiwimsy | 꿈 (IOI13_dreaming) | C++20 | 0 ms | 0 KiB |
#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
int rad;
vector<vector<pair<int, int>>> adj;
vector<bool> vis, dvis;
vector<int> diapath, diaedges;
vector<int> parent;
pair<int, int> get_furthest(int node){
dvis = vis;
queue<pair<int, int>> q;
int dist = 0, ret = 0;
q.push({node, 0});
while(!q.empty()){
pair<int, int> val = q.front();
q.pop();
for(pair<int, int> i : adj[val.first]){
if(!dvis[i.first]){
parent[i.first] = val.first;
q.push({i.first, i.second + val.second});
if(i.second + val.second > dist){
ret = i.first;
dist = i.second + val.second;
}
}
}
dvis[val.first] = true;
}
return {ret, dist};
}
int diameter(int node, int N){
diapath.clear(), diaedges.clear();
int a = 0, b = 0, dist = 0, p;
pair<int, int> dia;
a = get_furthest(node).first;
dia = get_furthest(a);
b = dia.first;
p = b;
while(p != a){
diapath.push_back(p);
for(pair<int, int> i : adj[p]) if(i.first == parent[p]) diaedges.push_back(i.second);
p = parent[p];
}
diapath.push_back(a);
vis = dvis;
return dia.second;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
adj.resize(N), parent.resize(N);
int ret = 0, bigcenter = 0, maxdia = 0;
vector<int> centers;
for(int i = 0; i < M; i++){
adj[A[i]].push_back({B[i], T[i]});
adj[B[i]].push_back({A[i], T[i]});
}
vis.assign(N, false), dvis = vis;
for(int i = 0; i < N; i++){
if(!vis[i]){
int dialength = diameter(i, N);
vis[i] = true;
int c = i, c1, c2, p = 0, mina, minb;
if(dialength > 0){
mina = dialength, minb = dialength;
for(int j = 0; j < diapath.size(); j++){
if(max(p, dialength - p) < mina){
c1 = diapath[j];
mina = max(p, dialength - p);
}
p += diaedges[j];
}
p = 0;
for(int j = diapath.size()-1; j >= 0; j--){
if(max(p, dialength - p) < mina){
c1 = diapath[j];
mina = max(p, dialength - p);
}
p += diaedges[j-1];
}
if(mina < minb) c = c1;
else c = c2;
}
if(dialength > maxdia){
bigcenter = c;
maxdia = dialength;
}
centers.push_back(c);
}
}
for(int i : centers){
if(i != bigcenter){
adj[i].push_back({bigcenter, L});
adj[bigcenter].push_back({i, L});
}
}
vis.assign(N, false);
return diameter(0, N);
}
int main(){
int n, m, l;
cin >> n >> m >> l;
int a[m], b[m], t[m];
for(int i = 0; i < m; i++){
cin >> a[i] >> b[i] >> t[i];
}
cout << travelTime(n, m, l, a, b, t) << endl;
}