#include "bits/stdc++.h"
#include "dreaming.h"
#define adj_list vector<list<pair<int, int>>>
#define vi vector<int>
using namespace std;
int nodes;
adj_list adj;
vi max_sub_dist, final_dist, trees;
void dfs1(int root) {
max_sub_dist[root] = 0;
for(auto& i : adj[root]) {
if(max_sub_dist[i.first]==-1) {
dfs1(i.first);
max_sub_dist[root] = max(max_sub_dist[root], max_sub_dist[i.first] + i.second);
}
}
}
int dfs2(int root) {
pair<int, int> maxi = make_pair(nodes, 0), smaxi = make_pair(nodes, 0);
for(auto& i : adj[root]) {
if(max_sub_dist[i.first]+i.second > max_sub_dist[maxi.first] + maxi.second) {
smaxi = maxi;
maxi = i;
}
else if(max_sub_dist[i.first]+i.second > max_sub_dist[smaxi.first] + smaxi.second) {
smaxi = i;
}
}
if(max_sub_dist[smaxi.first] + smaxi.second >= max_sub_dist[maxi.first])
return root;
max_sub_dist[maxi.first] = max(max_sub_dist[maxi.first], max_sub_dist[smaxi.first] + smaxi.second + maxi.second);
max_sub_dist[root] = max_sub_dist[smaxi.first] + smaxi.second;
return dfs2(maxi.first);
}
int diameter_dfs(int root, int state = 0) {
int maxi = root, node;
final_dist[root] = 0;
for(auto& i : adj[root]) {
if(final_dist[i.first]==-1) {
node = diameter_dfs(i.first, 1);
if(i.second + final_dist[i.first] > final_dist[root]) {
maxi = node;
final_dist[root] = i.second + final_dist[i.first];
}
}
}
if(state)
return maxi;
final_dist.assign(nodes, -1);
diameter_dfs(maxi, 1);
return maxi;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
nodes = N;
///constructing adjacency list --> O(N+M) ~ O(2N)
adj.assign(N, list<pair<int, int>> ());
for(int i = 0; i<M; i++) {
adj[A[i]].push_back(make_pair(B[i], T[i]));
adj[B[i]].push_back(make_pair(A[i], T[i]));
}
///finding the longest existing path from any node and selecting the minimum of those within a connected tree
///--> in order to find the longest path and simultaneously select, let us do two dfs such that the first
/// finds max distance in the subtree and the second finds the overall max distance O(6N)
max_sub_dist.assign(N+1, -1);
max_sub_dist[N] = 0;
int maxi = 0, node;
for(int i = 0; i<N; i++) {
if(max_sub_dist[i]==-1) {
dfs1(i);
node = dfs2(i);
if(max_sub_dist[node]>max_sub_dist[maxi])
maxi = node;
trees.push_back(node);
}
}
for (auto i : max_sub_dist) {
cout<<i<<" ";
}
cout<<endl;
for (auto & i : trees) {
cout<<i<<" ";
}
cout<<endl;
///since now, we already know the trees that exist, we just need to optimally merge them
for(int & tree : trees) {
if(tree!=maxi) {
adj[tree].push_back(make_pair(maxi, L));
adj[maxi].push_back(make_pair(tree, L));
}
}
///now that the trees are merged, let's just find the maximum distance (tree diameter), between any two nodes
final_dist.assign(N, -1);
node = diameter_dfs(maxi);
return final_dist[node];
}
int main() {
int n, l, m;
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;
}
Compilation message
/usr/bin/ld: /tmp/ccG8kJDJ.o: in function `main':
dreaming.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccd5uJHG.o:grader.c:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
