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OI-codes/S2OJ/1733/1733.cpp

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#include <iostream>
#include <algorithm>
#include <array>
#include <limits>
#include <queue>
#include <tuple>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 5e4 + 5,
Q = 3e5 + 5;
int n, q, k, l;
long long t;
std::tuple<int, int, int> edges[Q];
std::vector<int> ans;
std::array<std::vector<std::pair<int, long long>>, N> g;
std::array<bool, N> vis;
std::array<long long, N> dist;
void dijkstra() {
std::fill(vis.begin(), vis.end(), false);
std::fill(dist.begin(), dist.end(), std::numeric_limits<long long>::max() / 3);
std::priority_queue<std::pair<long long, int>, std::vector<std::pair<long long, int>>, std::greater<std::pair<long long, int>>> q;
q.emplace(0, 1);
dist[1] = 0;
while (!q.empty()) {
int u = q.top().second;
q.pop();
if (vis[u]) continue;
vis[u] = true;
for (auto e : g[u]) {
int v = e.first;
long long w = e.second;
if (dist[v] > dist[u] + w) {
dist[v] = dist[u] + w;
q.emplace(dist[v], v);
}
}
}
}
bool check(int l, int r) {
std::fill(g.begin(), g.end(), std::vector<std::pair<int, long long>>());
for (int i = l; i <= r; i++) {
int u = std::get<0>(edges[i]),
v = std::get<1>(edges[i]);
long long w = std::get<2>(edges[i]);
g[u].emplace_back(v, w);
g[v].emplace_back(u, w);
}
dijkstra();
return dist[n] <= t;
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> q >> t;
k = std::__lg(q) + 1;
for (int i = 1; i <= q; i++) {
cin >> std::get<0>(edges[i]) >> std::get<1>(edges[i]) >> std::get<2>(edges[i]);
}
while (l <= q) {
bool flag = false;
for (int i = 0; i <= k; i++) {
int r = std::min(l + (1 << i), q);
if (check(l, r)) {
int ql = i ? l + (1 << i - 1) : 0,
qr = l + (1 << i),
res = qr;
while (ql <= qr) {
int mid = (ql + qr) >> 1;
if (check(l, mid)) {
qr = mid - 1;
res = mid;
} else {
ql = mid + 1;
}
}
ans.emplace_back(res);
l = res + 1;
flag = true;
break;
}
if (r == q) break;
}
if (!flag) break;
}
cout << ans.size() << endl;
for (int x : ans) cout << x << ' ';
cout << endl;
return 0;
}