# | 제출 시각 | 아이디 | 문제 | 언어 | 결과 | 실행 시간 | 메모리 |
---|---|---|---|---|---|---|---|
1197453 | adiyer | Swapping Cities (APIO20_swap) | C++20 | 0 ms | 0 KiB |
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e5 + 11;
int n, m;
int p[MAXN], c[MAXN], sz[MAXN];
bool was[MAXN];
vector < int > cmp;
vector < int > g[MAXN], ver[MAXN], mn[MAXN], mx[MAXN];
vector < pair < int, pair < int, int > > > reb;
int get(int v, int t){
if(p[v] == v || c[v] > t) return v;
return get(p[v], t);
}
void unite(int a, int b, int t){
int pa = get(a, t), pb = get(b, t), x = mn[pa].back();
x -= (g[a].size() == 1), x -= (g[b].size() == 1);
g[a].push_back(b), g[b].push_back(a);
x += (g[a].size() == 1), x += (g[b].size() == 1);
if(pa != pb){
x += mn[pb].back();
if(sz[pa] > sz[pb]) swap(pa, pb);
sz[pb] += sz[pa], p[pa] = pb, c[pa] = t;
}
ver[pb].push_back(t), mn[pb].push_back(x), mx[pb].push_back(max({mx[pa].back(), mx[pb].back(), (int) g[a].size(), (int) g[b].size()}));
}
void init(int N, int M, vector < int > U, vector < int > V, vector < int > W){
n = N, m = M;
for(int i = 0; i < n; i++) p[i] = i, sz[i] = 1, ver[i].push_back(0), mn[i].push_back(0), mx[i].push_back(0);
for(int i = 0; i < m; i++) reb.push_back({W[i], {U[i], V[i]}});
sort(reb.begin(), reb.end());
for(int i = 0; i < m; i++){
auto [u, v] = reb[i].second;
unite(u, v, i);
}
}
void dfs(int v){
was[v] = 1, cmp.push_back(v);
for(int u : g[v])
if(!was[u])
dfs(u);
}
bool f(int x, int y, int t){
if(get(x, t) != get(y, t)) return 0;
x = get(x, t);
int pos = upper_bound(ver[x].begin(), ver[x].end(), t) - ver[x].begin();
return mx[x][pos - 1] > 2 || mn[x][pos - 1] == 0;
}
int getMinimumFuelCapacity(int X, int Y) {
int l = -1, r = m;
while(r - l > 1){
int md = (l + r) / 2;
if(f(X, Y, md)) r = md;
else l = md;
}
if(r == m) return -1;
return reb[r].first;
}
int main() {
int N, M;
assert(2 == scanf("%d %d", &N, &M));
std::vector<int> U(M), V(M), W(M);
for (int i = 0; i < M; ++i) {
assert(3 == scanf("%d %d %d", &U[i], &V[i], &W[i]));
}
int Q;
assert(1 == scanf("%d", &Q));
std::vector<int> X(Q), Y(Q);
for (int i = 0; i < Q; ++i) {
assert(2 == scanf("%d %d", &X[i], &Y[i]));
}
init(N, M, U, V, W);
std::vector<int> minimum_fuel_capacities(Q);
for (int i = 0; i < Q; ++i) {
minimum_fuel_capacities[i] = getMinimumFuelCapacity(X[i], Y[i]);
}
for (int i = 0; i < Q; ++i) {
printf("%d\n", minimum_fuel_capacities[i]);
}
return 0;
}