#include <bits/stdc++.h>
#define f0(i, n) for(int i=0; i<n; i++)
#define f1(i, n) for(int i=1; i<=n; i++)
#define fi first
#define se second
#define pb push_back
#define el cout << "\n";
#define sz(A) (int)A.size()
#define FOR(i, l, r) for (int i = l; i <= r; i++)
#define FOD(i, r, l) for (int i = r; i >= l; i--)
#define all(x) x.begin(), x.end()
#define faster \
ios_base::sync_with_stdio(false); \
cin.tie(NULL); \
cout.tie(NULL);
#define AWA signed main()
using namespace std;
typedef long long ll;
typedef pair<ll, ll> ii;
typedef unsigned long long ull;
typedef string str;
typedef vector<int> vi;
const int maxn=1000002;
const int mod=1000000007;
const ll inf = 1e18;
#define bit(mask, i) ((mask>>i)&1)
#define lon(x) ((1ll) << (x))
template <class X, class Y>
bool maximize(X &x, const Y&y)
{
if(x<y)
{
x=y;
return true;
}
else return false;
}
template <class X, class Y>
bool minimize(X &x, const Y&y)
{
if(x>y)
{
x=y;
return true;
}
else return false;
}
void file()
{
#define TASK "INCGRAPH"
if(fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
}
int n, m;
ll eu[maxn], ev[maxn], ew[maxn], Max[maxn];
vector<ii>adj[maxn];
struct Data{
ll dis[maxn];
void dijkstra(int s){
FOR(i, 1, n) dis[i] = inf;
dis[s] = 0;
priority_queue<ii, vector<ii>, greater<ii>> pq;
pq.push(make_pair(dis[s], s));
while(sz(pq)){
ii top = pq.top(); pq.pop();
int dd = top.fi, u = top.se;
for(ii it: adj[u]){
int v = it.fi, w = it.se;
if(dis[v] > dis[u] + w){
dis[v] = dis[u] + w;
pq.push(make_pair(dis[v], v));
}
}
}
}
}d1, dn;
int low[maxn], num[maxn], timer = 0;
bool contain[maxn];
vector<ii> g[maxn];
bool ok = 0;
void dfs(int s, int pre, ll mid){
if(s == n) contain[s] = 1;
low[s] = num[s] = ++timer;
for(ii it: g[s]){
int v = it.fi, id = it.se;
if(id == pre) continue;
if(!num[v]){
dfs(v, id, mid);
contain[s] |= contain[v];
low[s] = min(low[s], low[v]);
if(low[v] == num[v] && contain[v]){
if(d1.dis[eu[id]] + dn.dis[ev[id]] + ew[id] == d1.dis[n] && d1.dis[eu[id]] + dn.dis[ev[id]] + ew[id] + Max[id] >= d1.dis[n] + mid){
ok = 1;
}
}
}
else low[s] = min(low[s], num[v]);
}
}
bool check(ll mid){
FOR(i, 1, n){
g[i].clear();
low[i] = num[i] = 0;
contain[i] = 0;
}
timer = 0;
ok = 0;
f0(i, m){
ll u = eu[i], v = ev[i], w = ew[i];
if(d1.dis[u] + dn.dis[v] + ew[i] < d1.dis[n] + mid)
g[u].pb(make_pair(v, i)), g[v].pb(make_pair(u, i));
else if(d1.dis[v] + dn.dis[u] + ew[i] < d1.dis[n] + mid)
g[u].pb(make_pair(v, i)), g[v].pb(make_pair(u, i));
}
dfs(1, -1, mid);
return(ok);
}
AWA
{
faster;
file();
cin>>n>>m;
f0(i, m){
cin >> eu[i] >> ev[i] >> ew[i];
adj[eu[i]].pb(make_pair(ev[i], ew[i]));
adj[ev[i]].pb(make_pair(eu[i], ew[i]));
}
for(int i = m - 2; i >= 0; i--){
Max[i] = max(Max[i + 1], ew[i + 1]);
}
d1.dijkstra(1);
dn.dijkstra(n);
f0(i, m){
if(d1.dis[eu[i]] > d1.dis[ev[i]]) swap(eu[i], ev[i]);
}
ll l = 1, r = *max_element(ew + 1, ew + m + 1), ans = 0;
while(l <= r){
ll mid = (l + r) >> 1;
if(check(mid))
{
ans = mid;
l = mid + 1;
}
else r = mid - 1;
}
cout << d1.dis[n] + ans;
return 0;
}
컴파일 시 표준 에러 (stderr) 메시지
Aesthetic.cpp: In function 'void file()':
Aesthetic.cpp:54:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
54 | freopen(TASK".INP", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Aesthetic.cpp:55:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
55 | freopen(TASK".OUT", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
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