#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool mnto(T& a, T b) {return a > b ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}
#define REP(i, s, e) for (int i = s; i < e; i++)
#define RREP(i, s, e) for (int i = s; i >= e; i--)
typedef long long ll;
typedef long double ld;
#define MP make_pair
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
#define MT make_tuple
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
#ifdef DEBUG
#define debug(args...) printf(args)
#else
#define debug(args...)
#endif
#define INF 1000000005
#define LINF 1000000000000000005
#define MOD 1000000007
#define MAXN 300005
struct edge {
int v, w, p;
};
int n, m;
vector<edge> adj[MAXN];
int a[MAXN], b[MAXN], w[MAXN], p[MAXN];
ll base;
priority_queue<pll, vector<pll>, greater<pll>> pq;
ll d1[MAXN], dn[MAXN];
void dij(int s, ll* d) {
REP (i, 1, n + 1) {
d[i] = LINF;
}
d[s] = 0;
pq.push(MP(0, s));
while (!pq.empty()) {
auto [ud, u] = pq.top(); pq.pop();
if (ud != d[u]) continue;
for (edge e : adj[u]) {
if (mnto(d[e.v], ud + e.w)) {
pq.push(MP(d[e.v], e.v));
}
}
}
}
ll x;
bool res;
int pre[MAXN], top[MAXN], ptr;
vector<edge> nadj[MAXN];
void dfs(int u, int p) {
pre[u] = top[u] = ptr++;
for (edge e : nadj[u]) {
if (e.v == p) continue;
if (pre[e.v] == -1) {
dfs(e.v, u);
mnto(top[u], top[e.v]);
if (top[e.v] > pre[u]) {
if (min(d1[u] + dn[e.v], d1[e.v] + dn[u])
+ e.w + e.p >= x + base) {
res = 1;
}
}
} else {
mnto(top[u], pre[e.v]);
}
}
}
bool isPos(ll x) {
REP (i, 1, n + 1) {
nadj[i].clear();
}
debug("%lld\n", x);
REP (i, 0, m) {
if (min(d1[a[i]] + dn[b[i]], d1[b[i]] + dn[a[i]]) + w[i] < x + base) {
debug(" %d %d %d\n", a[i], b[i], p[i]);
debug(" %lld + %d + %d\n", min(d1[a[i]] + dn[b[i]], d1[b[i]] + dn[a[i]]), w[i], p[i]);
nadj[a[i]].pb({b[i], w[i], p[i]});
nadj[b[i]].pb({a[i], w[i], p[i]});
}
}
ptr = 0;
::x = x;
res = 0;
memset(pre, -1, sizeof pre);
REP (i, 1, n + 1) {
if (pre[i] == -1) {
dfs(i, -1);
}
}
return res;
}
int main() {
scanf("%d%d", &n, &m);
REP (i, 0, m) {
scanf("%d%d%d", &a[i], &b[i], &w[i]);
}
int mx = 0;
RREP (i, m - 1, 0) {
p[i] = mx;
mxto(mx, w[i]);
}
REP (i, 0, m) {
adj[a[i]].pb({b[i], w[i], p[i]});
adj[b[i]].pb({a[i], w[i], p[i]});
}
dij(1, d1);
dij(n, dn);
base = d1[n];
ll lo = 0, hi = INF, mid;
while (lo < hi) {
mid = lo + hi + 1 >> 1;
if (isPos(mid)) {
lo = mid;
} else {
hi = mid - 1;
}
}
printf("%lld\n", base + lo);
return 0;
}
Compilation message
Aesthetic.cpp: In function 'int main()':
Aesthetic.cpp:131:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
131 | mid = lo + hi + 1 >> 1;
| ~~~~~~~~^~~
Aesthetic.cpp:113:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
113 | scanf("%d%d", &n, &m);
| ~~~~~^~~~~~~~~~~~~~~~
Aesthetic.cpp:115:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
115 | scanf("%d%d%d", &a[i], &b[i], &w[i]);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
9 ms |
15564 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
9 ms |
15564 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
577 ms |
44952 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
619 ms |
45632 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
2080 ms |
61024 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Execution timed out |
2080 ms |
61024 KB |
Time limit exceeded |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
9 ms |
15564 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
