#pragma GCC optimize("O1,O2,O3,Ofast,unroll-loops")
#include "dreaming.h"
#include <bits/stdc++.h>
#include <string>
#include <iostream>
#include <cmath>
#include <numeric>
#include <iomanip>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<int, int> pl;
typedef pair<ld, ld> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<ld> vd;
typedef vector<long> vl;
typedef vector<ull> vull;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<vpi> vvpi;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define len(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define F first
#define nl endl
#define S second
#define lb lower_bound
#define ub upper_bound
#define aint(x) x.begin(), x.end()
#define raint(x) x.rbegin(), x.rend()
#define ins insert
const int MOD = 1000000007;
vi visited;
vvpi paths;
vi prev_arr;
int node = 0;
int maxdist = 0;
int ans = 0;
int n;
map<pair<int,int>,int> cons;
vi dist,prev_arr;
void dij(int pos){
queue<int> p;
p.push(pos);
dist[pos] = 0;
while(!p.empty()){
int a = p.front();p.pop();
visited[a] = 1;
for(auto b:paths[a]){
if(a!= pos && prev_arr[a] == b.F)continue;
dist[b.F] = dist[a] + b.S;
p.push(b.F);
prev_arr[b.F] = a;
if(dist[b.F] > maxdist){
maxdist = dist[b.F];
node = b.F;
}
}
}
}
// void dij2(int pos,int mxdst){
// vi dist(n,-1);
// vi dist2(n,-1);
// prev_arr = vi(n,-1);
// queue<int> p;
// p.push(pos);
// dist[pos] = 0;
// dist2[pos] = mxdst;
// while(!p.empty()){
// int a = p.front();p.pop();
// for(auto b:paths[a]){
// if(backtrack.count(b.F) == 0)continue;
// if(a!= pos && prev_arr[a] == b.F)continue;
// dist[b.F] = dist[a] + b.S;
// dist2[b.F] = dist2[a] - b.S;
// p.push(b.F);
// prev_arr[b.F] = a;
// if(max(dist[b.F],dist2[b.F]) < maxdist){
// maxdist = max(dist[b.F],dist2[b.F]);
// node = b.F;
// }
// }
// }
// }
void go_back(int pos,int counter1){
int counter2 = 0;
while(prev_arr[pos] != -1){
counter1 -= cons[{min(pos,prev_arr[pos]),max(pos,prev_arr[pos])}];
counter2 += cons[{min(pos,prev_arr[pos]),max(pos,prev_arr[pos])}];
maxdist = min(max(counter1,counter2),maxdist);
pos = prev_arr[pos];
}
}
int travelTime(int N, int m, int L, int A[], int B[], int T[]) {
if(n==1)return 0;
n = N;
dist.resize(n,-1);
prev_arr.resize(n,-1);
paths = vvpi(n);
visited = vi(n,0);
vi distances(n,0);
ans = 0;
int cnt = 0;
FOR(i,0,m){
cons[{min(A[i],B[i]),max(A[i],B[i])}] = T[i];
paths[A[i]].pb({B[i],T[i]});
paths[B[i]].pb({A[i],T[i]});
}
for(int i=0;i<n;i++){
if(visited[i])continue;
maxdist = 0;
node = i;
dij(i);
// cerr << i << " " << node << " " << maxdist << endl;
maxdist = 0;
int head = node;
node = i;
dij(head);
// cerr << "width " << head << " " << node << " " << maxdist << endl;
ans = max(ans,maxdist);
// backtrack.clear();
go_back(node,maxdist);
// cerr << "path - ";
// for(int a:backtrack)cerr << a << " ";
// cerr << endl;
// dij2(node,maxdist);
// head = node;
// maxdist = 0;
// dij(head);
// cerr << "center " << head << " " << maxdist << endl;
// cerr << endl;
distances[i] = maxdist;
cnt += 1;
}
sort(distances.rbegin(),distances.rend());
if(m == n-1)return ans;
if(cnt >= 2)ans = max(ans,distances[0]+distances[1]+L);
if(cnt >= 3)ans = max(ans,distances[1]+distances[2]+L+L);
return ans;
}
Compilation message
dreaming.cpp:52:9: error: redefinition of 'vi prev_arr'
52 | vi dist,prev_arr;
| ^~~~~~~~
dreaming.cpp:46:4: note: 'vi prev_arr' previously declared here
46 | vi prev_arr;
| ^~~~~~~~
