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>
template <class T>
using Vec = std::vector<T>;
struct DSU {
Vec<int> par;
std::stack<std::pair<int, int>> past;
DSU(const int n): par(n, -1) { }
int find(int u) const {
while (par[u] >= 0) {
u = par[u];
}
return u;
}
int find_notrack(const int u) {
return par[u] < 0 ? u : par[u] = find_notrack(par[u]);
}
int merge(int x, int y) {
x = find(x);
y = find(y);
if (x == y) {
return 0;
}
if (par[x] > par[y]) {
std::swap(x, y);
}
past.emplace(x, par[x]);
past.emplace(y, par[y]);
par[x] += par[y];
par[y] = x;
return 2;
}
void merge_notrack(int x, int y) {
x = find_notrack(x);
y = find_notrack(y);
if (x == y) {
return;
}
if (par[x] > par[y]) {
std::swap(x, y);
}
par[x] += par[y];
par[y] = x;
}
int comp(const int x) const {
return -par[find(x)];
}
void rollback() {
while (!past.empty()) {
const auto [i, v] = past.top();
past.pop();
par[i] = v;
}
}
};
int scan() {
int x;
std::scanf("%d", &x);
return x;
}
constexpr int BSIZE = 600;
int main() {
const auto N = scan();
const auto M = scan();
Vec<int> U(M), V(M), D(M);
for (int i = 0; i < M; ++i) {
U[i] = scan() - 1;
V[i] = scan() - 1;
D[i] = scan();
}
const auto Q = scan();
Vec<int> T(Q), K(Q), W(Q);
for (int i = 0; i < Q; ++i) {
T[i] = scan();
K[i] = scan() - 1;
W[i] = scan();
}
const auto Steps = (Q + BSIZE - 1) / BSIZE;
Vec<int> ans;
ans.reserve(Q);
Vec<bool> dyn(M);
Vec<int> still(M);
std::iota(still.begin(), still.end(), 0);
for (int step = 0; step < Steps; ++step) {
const auto qL = step * BSIZE;
const auto qR = std::min((step + 1) * BSIZE, Q);
Vec<int> set;
Vec<std::pair<int, int>> ask;
set.reserve(qR - qL);
ask.reserve(qR - qL);
for (int i = qL; i < qR; ++i) {
if (T[i] == 1) {
set.push_back(i);
dyn[K[i]] = true;
}
else {
ask.emplace_back(i, (int) ans.size());
ans.push_back(0);
}
}
std::sort(ask.begin(), ask.end(), [&](const auto &q1, const auto &q2) {
return W[q1.first] > W[q2.first];
});
Vec<int> change;
change.reserve(qR - qL);
for (int i = 0; i < M; ++i) {
if (dyn[i]) {
change.push_back(i);
}
}
std::sort(still.begin(), still.end(), [&](const int i, const int j) {
return D[i] < D[j];
});
DSU dsu(N);
int still_idx = (int) still.size();
for (const auto [idx, ptr]: ask) {
while (still_idx > 0) {
const auto i = still[still_idx - 1];
if (dyn[i]) {
still_idx -= 1;
continue;
}
if (W[idx] > D[i]) {
break;
}
still_idx -= 1;
dsu.merge_notrack(U[i], V[i]);
}
std::stack<std::pair<int, int>> past;
for (const auto i: set) {
if (i > idx) {
break;
}
past.emplace(K[i], D[K[i]]);
D[K[i]] = W[i];
}
for (const auto i: change) {
if (W[idx] <= D[i]) {
dsu.merge(U[i], V[i]);
}
}
ans[ptr] = dsu.comp(K[idx]);
dsu.rollback();
while (!past.empty()) {
const auto [i, v] = past.top();
past.pop();
D[i] = v;
}
}
for (const auto i: set) {
D[K[i]] = W[i];
dyn[K[i]] = false;
}
}
for (const auto x: ans) {
std::printf("%d\n", x);
}
return 0;
}
Compilation message (stderr)
bridges.cpp: In function 'int scan()':
bridges.cpp:60:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
60 | std::scanf("%d", &x);
| ~~~~~~~~~~^~~~~~~~~~
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