# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1275306 | desmond1015 | Dreaming (IOI13_dreaming) | C++20 | 0 ms | 0 KiB |
#include "bits/stdc++.h"
using namespace std;
#define ll long long
#include "dreaming.h"
int MOD = 1e9+7;
int INF = 1e9;
void solve() {
int n, m, l;
cin >> n >> m >> l;
vector<array<int, 2>> g[n];
for (int i = 0; i < m; i++) {
int a, b, t;
cin >> a >> b >> t;
g[a].push_back({b, t});
g[b].push_back({a, t});
}
vector<ll> mx(n), smx(n);
vector<int> compId(n);
vector<bool> vis(n);
int cc = 0;
function<void(int)> dfs1 = [&](int u) {
vis[u] = true;
compId[u] = cc;
for (auto [v, t] : g[u]) {
if (vis[v]) continue;
dfs1(v);
if (mx[v] + t > mx[u]) {
smx[u] = mx[u];
mx[u] = mx[v] + t;
} else if (mx[v] + t > smx[u]) {
smx[u] = mx[v] + t;
}
}
};
for (int i = 0; i < n; i++) {
if (vis[i]) continue;
dfs1(i);
cc++;
}
function<void(int)> dfs2 = [&](int u) {
vis[u] = true;
for (auto [v, t] : g[u]) {
if (vis[v]) continue;
if (mx[v] + t == mx[u]) {
if (smx[u] + t > mx[v]) {
smx[v] = mx[v];
mx[v] = smx[u] + t;
} else if (smx[u] + t > smx[v]) {
smx[v] = smx[u] + t;
}
} else {
if (mx[u] + t > mx[v]) {
smx[v] = mx[v];
mx[v] = mx[u] + t;
} else if (mx[u] + t > smx[v]) {
smx[v] = mx[u] + t;
}
}
dfs2(v);
}
};
vis.assign(n, false);
for (int i = 0; i < n; i++) {
if (vis[i]) continue;
dfs2(i);
}
vector<ll> comp(cc, 1e17);
for (int i = 0; i < n; i++) {
int id = compId[i];
comp[id] = min(comp[id], mx[i]);
}
sort(comp.rbegin(), comp.rend());
assert(cc > 1);
ll ans = comp[0] + comp[1] + l;
cout << ans << '\n';
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
// freopen("input.in", "r", stdin);
// freopen("output.out", "w", stdout);
// int T = 1;
// cin >> T;
// while (T--) {
solve();
// }
return 0;
}