| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1074520 | TB_ | Highway Tolls (IOI18_highway) | C++17 | 0 ms | 0 KiB |
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>
#pragma GCC optimize("Ofast,inline")
using namespace std;
#define ll long long
#define fo(i, n) for(ll i = 0; i<(n); i++)
#define pb push_back
#define F first
#define S second
#define deb(x) cout << #x << " = " << (x) << endl
#define deb2(x, y) cout << #x << " = " << (x) << ", " << #y << " = " << (y) << endl
typedef vector<ll> vl;
typedef vector<vl> vvl;
namespace {
constexpr int MAX_NUM_CALLS = 100;
constexpr long long INF = 1LL << 61;
int N, M, A, B, S, T;
std::vector<int> U, V;
std::vector<std::vector<std::pair<int, int>>> graph;
bool answered, wrong_pair;
int num_calls;
int read_int() {
int x;
if (scanf("%d", &x) != 1) {
fprintf(stderr, "Error while reading input\n");
exit(1);
}
return x;
}
void wrong_answer(const char *MSG) {
printf("Wrong Answer: %s\n", MSG);
exit(0);
}
} // namespace
long long ask(const std::vector<int> &w) {
if (++num_calls > MAX_NUM_CALLS) {
wrong_answer("more than 100 calls to ask");
}
if (w.size() != (size_t)M) {
wrong_answer("w is invalid");
}
for (size_t i = 0; i < w.size(); ++i) {
if (!(w[i] == 0 || w[i] == 1)) {
wrong_answer("w is invalid");
}
}
std::vector<bool> visited(N, false);
std::vector<long long> current_dist(N, INF);
std::queue<int> qa, qb;
qa.push(S);
current_dist[S] = 0;
while (!qa.empty() || !qb.empty()) {
int v;
if (qb.empty() ||
(!qa.empty() && current_dist[qa.front()] <= current_dist[qb.front()])) {
v = qa.front();
qa.pop();
} else {
v = qb.front();
qb.pop();
}
if (visited[v]) {
continue;
}
visited[v] = true;
long long d = current_dist[v];
if (v == T) {
return d;
}
for (auto e : graph[v]) {
int vv = e.first;
int ei = e.second;
if (!visited[vv]) {
if (w[ei] == 0) {
if (current_dist[vv] > d + A) {
current_dist[vv] = d + A;
qa.push(vv);
}
} else {
if (current_dist[vv] > d + B) {
current_dist[vv] = d + B;
qb.push(vv);
}
}
}
}
}
return -1;
}
void answer(int s, int t) {
if (answered) {
wrong_answer("answered not exactly once");
}
if (!((s == S && t == T) || (s == T && t == S))) {
wrong_pair = true;
}
answered = true;
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
int M = U.size();
vl invalid(N, 0);
for (int j = 0; j < 50; ++j) {
std::vector<int> w(M);
for (int i = 0; i < M; ++i) {
w[i] = rand()%2;
}
long long toll = ask(w);
// deb(toll);
queue<pair<ll, ll>> pq;
pq.push({0, 0});
vl seen(N, 0);
ll cost, pos;
vector<vector<pair<ll, ll>>> adj(N);
fo(i, M){
adj[U[i]].pb({V[i], (w[i]?B:A)});
adj[V[i]].pb({U[i], (w[i]?B:A)});
}
while(!pq.empty()){
tie(cost, pos) = pq.front();
pq.pop();
cost = -cost;
if(seen[pos]) continue;
// deb2(pos, cost);
invalid[pos]|=cost!=toll;
seen[pos] = 1;
for(auto &[v, w] : adj[pos]){
pq.push({-cost-w, v});
}
}
}
int ans = 0;
fo(i, N) if(!invalid[i]) ans = i;
// fo(i, N) deb(invalid[i]);
answer(0, ans);
}
int main() {
N = read_int();
M = read_int();
A = read_int();
B = read_int();
S = read_int();
T = read_int();
U.resize(M);
V.resize(M);
graph.assign(N, std::vector<std::pair<int, int>>());
for (int i = 0; i < M; ++i) {
U[i] = read_int();
V[i] = read_int();
graph[U[i]].push_back({V[i], i});
graph[V[i]].push_back({U[i], i});
}
answered = false;
wrong_pair = false;
num_calls = 0;
find_pair(N, U, V, A, B);
if (!answered) {
wrong_answer("answered not exactly once");
}
if (wrong_pair) {
wrong_answer("{s, t} is wrong");
}
printf("Accepted: %d\n", num_calls);
return 0;
}