#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define pll pair<long long, long long>
const int sz = 1e5 + 5;
vector<pll> gr[sz];
long long n, m, S, T, U, V;
long long dp[5][sz];
long long d[5][sz];
//constants
long long INF;
long long ST;
// ------------- FUNCTIONS ------------- //
void Dijkstra(int s, int k){
priority_queue<pll> q;
d[k][s] = 0;
q.push({0, s});
while(q.size()){
long long w, u;
tie(w, u) = q.top();
w = -w;
q.pop();
if(w > d[k][u]){
continue;
}
for(pll p : gr[u]){
long long v, c;
tie(v, c) = p;
if(w + c < d[k][v]){
d[k][v] = w + c;
q.push({-d[k][v], v});
}
}
}
}
vector<int> dag[sz];
int vi[sz];
void build_DAG(int v){
// vi[v] = 1;
// for(pll p : gr[v]){
// long long u, c;
// tie(u, c) = p;
// if(d[0][u] + c + d[1][v] == ST){
// dag[u].push_back(v);
// if(vi[u] == 0){
// build_DAG(u);
// }
// }
// }
vector<long long> d_dag(n + 5, INF);
priority_queue<pll> q;
q.push({0, S});
d_dag[S] = 0;
while(q.size()){
long long w, u;
tie(w, u) = q.top();
w = -w;
q.pop();
if(w > d_dag[u]){
continue;
}
for(pll p : gr[u]){
long long v, c;
tie(v, c) = p;
if(w + c < d_dag[v]){
d_dag[v] = w + c;
q.push({-d_dag[v], v});
dag[u].clear();
dag[v].push_back(u);
}
else if(w + c == d_dag[v]){
dag[v].push_back(u);
}
}
}
}
void topo(int u){
vi[u] = 2;
for(int v : dag[u]){
dp[1][u] = min(dp[1][u], dp[1][v]);
dp[2][u] = min(dp[2][u], dp[2][v]);
if(vi[v] != 2){
topo(v);
}
}
priority_queue<pll> q;
}
// ------------- SUBTASK ------------- //
namespace SUB1{
bool ok(){
return (S == U);
}
void solve(){
Dijkstra(V, 3);
long long ans = 1e18;
for(int i=1;i<=n;++i){
if(d[0][i] + d[1][i] == d[0][T]){
ans = min(ans, d[3][i]);
}
}
cout<<ans;
//--------------------
exit(0);
}
}
long long ds2[305][305];
namespace SUB2{ // n <= 300
bool ok(){
return (n <= 300);
}
void solve(){
memset(ds2, 63, sizeof(ds2));
for(int i=1;i<=n;++i){
ds2[i][i] = 0;
for(pll p : gr[i]){
ds2[i][p.first] = p.second;
}
}
// Floyd - Warshall
for(int k=1;k<=n;++k){
for(int i=1;i<=n;++i){
for(int j=1;j<=n;++j){
ds2[i][j] = min(ds2[i][j], ds2[i][k] + ds2[k][j]);
}
}
}
long long ans = ds2[U][V];
for(int i=1;i<=n;++i){
for(int j=1;j<=n;++j){
if(ds2[S][i] + ds2[i][j] + ds2[j][T] == ST){
ans = min(ans, ds2[U][i] + ds2[j][V]);
ans = min(ans, ds2[U][j] + ds2[i][V]);
}
}
}
cout<<ans;
//----------------------
exit(0);
}
}
namespace SUB3{
void solve(){
build_DAG(T);
Dijkstra(U, 3);
Dijkstra(V, 4);
memset(dp, 63, sizeof(dp));
for(int i=1;i<=n;++i){
dp[1][i] = d[3][i];
dp[2][i] = d[4][i];
}
// topo(S);
long long ans = d[3][V];
priority_queue<pll> q;
ds3 = vector<long long>(n + 5, INF);
ds3[T] = d[4][T];
while(q.size()){
long long w, u;
tie(w, u) = q.top();
w = -w;
q.pop();
if(w > ds3[u]){
continue;
}
ans = min(ans, w + d[4][u]);
for(int v : dag[u]){
long long c = min(w, d[4][u]);
if(c < ds3[v]){
ds3[v] = c;
q.push({-c, v});
}
}
}
ds3 = vector<long long>(n + 5, INF);
ds3[T] = d[3][T];
while(q.size()){
long long w, u;
tie(w, u) = q.top();
w = -w;
q.pop();
if(w > ds3[u]){
continue;
}
ans = min(ans, w + d[3][u]);
for(int v : dag[u]){
long long c = min(w, d[3][u]);
if(c < ds3[v]){
ds3[v] = c;
q.push({-c, v});
}
}
}
// for(int i=1;i<=n;++i){
// ans = min({ans, dp[1][i] + d[4][i], dp[2][i] + d[3][i]});
// }
cout<<ans;
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// freopen("PATHLIB.inp","r",stdin);
//freopen("PATHLIB.out","w",stdout);
cin >> n >> m;
cin >> S >> T;
cin >> U >> V;
for(int i=1;i<=m;++i){
int u, v, c;
cin>>u>>v>>c;
gr[u].push_back({v, c});
gr[v].push_back({u, c});
}
memset(d, 63, sizeof(d));
INF = d[0][0];
Dijkstra(S, 0);
Dijkstra(T, 1);
ST = d[0][T];
if(SUB1::ok()){ //S == U
SUB1::solve();
}
if(SUB2::ok()){ //n <= 300
SUB2::solve();
}
SUB3::solve();
return 0;
}
Compilation message
commuter_pass.cpp: In function 'void SUB3::solve()':
commuter_pass.cpp:183:9: error: 'ds3' was not declared in this scope; did you mean 'ds2'?
183 | ds3 = vector<long long>(n + 5, INF);
| ^~~
| ds2
