This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#define int long long
using namespace std;
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define rep(i, a, b) for(int i = (a); i < (b); i++)
#define sz(v) ((int)((v).size()))
template<typename T>
void chmax(T &x, const T &v) { if (x < v) x = v; }
template<typename T>
void chmin(T &x, const T &v) { if (x > v) x = v; }
using pii = pair<int, int>;
using vi = vector<int>;
string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
bool first = true;
string res = "[";
for (const auto &x : v) {
if (!first)
res += ", ";
first = false;
res += to_string(x);
}
res += "]";
return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
cout << ' ' << to_string(H);
dbg_out(T...);
}
#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif
const int MAX_N = 2005, MAX_ARRET = 1 << 17;
int nbNode, nbEdge, nbReq, nbArret;
vector<int> adj[MAX_N];
int xorNode[MAX_N];
int poids[MAX_N];
int arrets[MAX_ARRET];
int vus[MAX_N][MAX_N];
int VuTime = 0;
struct Chemin {
int len, fst, lst;
bool operator<(const Chemin &oth) const {
return tie(len, fst, lst) < tie(oth.len, oth.fst, oth.lst);
}
bool operator==(const Chemin &oth) const {
return tie(len, fst, lst) == tie(oth.len, oth.fst, oth.lst);
}
};
template<typename T>
using minpq = priority_queue<T, vector<T>, greater<T>>;
string to_string(const Chemin c) {
return "(len=" + to_string(c.len) + ", fst=" + to_string(c.fst) + ", lst=" + to_string(c.lst) + ")";
}
int cntFirst[MAX_N + 1], cntLast[MAX_N + 1];
vector<Chemin> compressTab (vector<Chemin> &chemins) {
#ifdef DEBUG
assert(is_sorted(all(chemins)));
#endif
VuTime++;
vector<Chemin> ret;
for (Chemin chem : chemins) {
if (ret.size() > 8)
break;
dbg(chem);
if (cntFirst[1+chem.fst] == 3 or cntLast[1+chem.lst] == 3 or vus[1+chem.fst][1+chem.lst] == VuTime)
continue;
ret.push_back(chem);
cntFirst[1+chem.fst]++;
cntLast[1+chem.lst]++;
vus[1+chem.fst][1+chem.lst] = VuTime;
}
for (Chemin chem : ret) {
cntFirst[1+chem.fst]--;
cntLast[1+chem.lst]--;
}
return ret;
};
/// i-eme feuille = candidats pour X[i] -> X[i+1]
vector<Chemin> tree[2*MAX_ARRET];
const int sizeTree = MAX_ARRET;
vector<Chemin> merge(const vector<Chemin> &v1, const vector<Chemin> &v2) {
vector<Chemin> nv;
for (const Chemin &c1 : v1) for (const Chemin &c2 : v2) {
if (c1.lst != c2.fst) {
int newFst = (c1.fst == -1 ? c2.fst : c1.fst);
nv.push_back({c1.len + c2.len, newFst, c2.lst});
}
}
sort(all(nv));
return compressTab(nv);
}
int leftRightLeaf(int idx) {
if (idx < sizeTree) idx = 2*idx+1;
while (idx < sizeTree) idx *= 2;
return idx - sizeTree;
}
void _recalc(int idx) {
if (leftRightLeaf(idx) >= nbArret-1) { // todo check
tree[idx] = tree[2*idx];
} else {
tree[idx] = merge(tree[2*idx], tree[2*idx+1]);
}
}
void buildTree() {
for (int node = sizeTree-1; node >= 1; --node) {
_recalc(node);
}
}
void update(int idx, vector<Chemin> v) {
idx += sizeTree;
tree[idx] = v;
while (idx > 1) {
idx /= 2;
_recalc(idx);
}
}
vector<Chemin> matrice[MAX_N][MAX_N];
void buildMatrice() {
auto interesting = [&] (const Chemin &add, vector<Chemin> &V) {
V.insert(upper_bound(all(V), add), add);
V = compressTab(V);
return (find(all(V), add) != end(V));
};
rep(depart, 0, nbNode) {
auto& cand = matrice[depart];
cand[depart].push_back({0, -1, -1});
minpq<pair<Chemin, int>> pq;
pq.push({cand[depart].back(), depart});
vector<int> nbVus(nbNode);
while (!pq.empty()) {
auto [oldChemin, node] = pq.top();
pq.pop();
nbVus[node]++;
// oldChemin.len == dist[node]
dbg(depart, node);
if (find(all(cand[node]), oldChemin) == end(cand[node])) {
continue;
}
for (int iEdge : adj[node]) {
if (iEdge == oldChemin.lst) continue;
int voisin = xorNode[iEdge]^node;
Chemin nouvChemin {
oldChemin.len + poids[iEdge],
(oldChemin.fst == -1 ? iEdge : oldChemin.fst),
iEdge
};
if (interesting(nouvChemin, cand[voisin])) {
dbg(voisin, cand[voisin], nouvChemin);
pq.push({nouvChemin, voisin});
}
}
}
rep(node, 0, nbNode) {
cand[node] = compressTab(cand[node]);
assert(sz(cand[node]) <= 9);
}
}
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> nbNode >> nbEdge >> nbReq >> nbArret;
rep(iEdge, 0, nbEdge) {
int u, v; cin >> u >> v;
--u, --v;
cin >> poids[iEdge];
xorNode[iEdge] = u^v;
adj[u].push_back(iEdge);
adj[v].push_back(iEdge);
}
buildMatrice();
rep(iArret, 0, nbArret) {
cin >> arrets[iArret];
--arrets[iArret];
if (iArret > 0) {
tree[sizeTree + iArret-1] = matrice[arrets[iArret-1]][arrets[iArret]];
}
}
buildTree();
rep(iReq, 0, nbReq) {
int indice, val;
cin >> indice >> val;
--indice, --val;
arrets[indice] = val;
if (indice > 0) {
update(indice-1, matrice[arrets[indice-1]][arrets[indice]]);
}
if (indice+1 < nbArret) {
update(indice, matrice[arrets[indice]][arrets[indice+1]]);
}
int ans = -1;
if (!tree[1].empty()) ans = tree[1].front().len;
cout << ans << '\n';
}
}
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