#include<bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
#define pii pair<int,int>
#define ll long long
#define pb push_back
#define vi vector<int>
#define se second
#define fi first
using namespace std;
const int N = 1e5+5;
vector<pii> adj[N];
int n,m;
int A[N],B[N],W[N],NUM[N][2],MX[N],par[N],good[N],sub[N],id[N];
ll D[N],FROM_N[N];
set<pii> path;
void dijkstra(int s) {
priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > pq;
pq.push({0,s});
vector<bool> vis(n+1);
vector<ll> d(n+1);
for (int i = 1; i <= n; i++)
d[i] = 10000000000000000;
d[s] = 0;
par[s] = 0;
id[s] = 0;
while(!pq.empty()) {
auto i1 = pq.top();
pq.pop();
int v = i1.se;
if (vis[v]) continue;
ll dis = i1.fi;
vis[v] = 1;
for (auto i : adj[v])
if (!vis[i.fi] && d[i.fi] > dis + i.se) {
d[i.fi] = dis + i.se;
id[i.fi] = id[v] + 1;
par[i.fi] = v;
pq.push({d[i.fi],i.fi});
}
}
if (s == n)
for (int i = 1; i <= n; i++)
FROM_N[i] = d[i];
else {
for (int i = 2; i <= n; i++) {
path.insert({i,par[i]});
path.insert({par[i],i});
}
for (int i = 1; i <= n; i++)
D[i] = d[i];
int j = n;
good[1] = 1;
while(j != 1) {
good[j] = 1;
j = par[j];
}
vector<pair<ll,int> > g;
for (int i =1 ; i <= n; i++) {
g.pb({d[i],i});
}
sort(all(g));
for (auto i1 : g) {
int v = i1.se;
if (!good[v])
sub[v] = sub [ par[v] ];
else sub[v] = v;
}
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for (int i = 0; i < m; i++) {
int a,b,w;
cin >> a >> b >> w;
A[i] = a, B[i] = b;
W[i] = w;
NUM[i][0] = adj[a].size();
NUM[i][1] = adj[b].size();
adj[a].pb({b,w});
adj[b].pb({a,w});
MX[i] = w;
}
dijkstra(n);
dijkstra(1);
// cout << FROM_N[1];exit(0);
for (int i = m-2; i >= 0; i--)
MX[i] = max(MX[i],MX[i+1]);
ll ans = 0;
// cout << D[n];exit(0);
/*for (int i = 0; i < m; i++) {
int a = A[i], b = B[i];
adj[a][NUM[i][0]].se += MX[i+1];
adj[b][NUM[i][1]].se += MX[i+1];
// dijkstra
priority_queue<pair<ll,int>,vector<pair<ll,int> >,greater<pair<ll,int> > > pq;
pq.push({0,1});
vector<bool> vis(n+1);
vector<ll> d(n+1);
for (int i = 1; i <= n; i++)
d[i] = 10000000000000000;
d[1] = 0;
while(!pq.empty()) {
auto i1 = pq.top();
pq.pop();
int v = i1.se;
if (vis[v]) continue;
ll dis = i1.fi;
if (v == n) {
ans = max(ans,dis);
break;
}
vis[v] = 1;
for (auto i : adj[v])
if (!vis[i.fi] && d[i.fi] > dis + i.se) {
d[i.fi] = dis + i.se;
pq.push({d[i.fi],i.fi});
}
}
// replace
adj[a][NUM[i][0]].se -= MX[i+1];
adj[b][NUM[i][1]].se -= MX[i+1];
}*/
for (int i = 0; i < m; i++) {
int a = A[i], b = B[i];
if (path.count({a,b}) == 0) continue;
if (id[a] > id[b]) swap(a,b);
ll C = D[n];
C += MX[i+1];
//adj[a][NUM[i][0]].se += MX[i+1];
//adj[b][NUM[i][1]].se += MX[i+1];
// dijkstra
for (int i = 0; i < m; i++) {
int x = A[i], y = B[i];
if (id[sub[x]] > id[sub[y]]) swap(x,y);
if (x == a && y == b ) continue;
if (id[sub[x]] > id[a] || id[sub[y]] < id[b]) continue;
C = min(C,D[x] + FROM_N[y] + W[i]);
}
ans = max(ans,C);
}
// replace
//adj[a][NUM[i][0]].se -= MX[i+1];
//adj[b][NUM[i][1]].se -= MX[i+1];
cout << ans;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
2 ms |
2688 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
2 ms |
2688 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
6 ms |
5248 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
6 ms |
5248 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
6 ms |
5248 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Runtime error |
6 ms |
5248 KB |
Execution killed with signal 11 |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
2 ms |
2688 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
