| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 529105 | rk42745417 | Olympic Bus (JOI20_ho_t4) | 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>
using namespace std;
#define EmiliaMyWife ios::sync_with_stdio(0); cin.tie(0);
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using ld = long double;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const ll LINF = ll(4e18) + ll(2e15);
const double EPS = 1e-9;
static int LamyIsCute = []() {
EmiliaMyWife
return 48763;
}();
signed main() {
int n, m;
cin >> n >> m;
vector<vector<pair<int, int>>> edge(n + 1);
vector<vector<bool>> can(n + 1, vector<bool>(n + 1));
vector<tuple<int, int, int, int>> edges(m);
for(int i = 0, u, v, c, d; i < m; i++) {
cin >> u >> v >> c >> d;
edge[u].push_back({v, c});
edges[i] = {u, v, c, d};
}
for(int i = 1; i <= n; i++) {
can[i][i] = true;
queue<int> bfs;
bfs.push(i);
while(!bfs.empty()) {
int u = bfs.front();
bfs.pop();
for(const auto &[v, c] : edge[u]) {
if(!can[i][v]) {
can[i][v] = true;
bfs.push(v);
}
}
}
}
if(vis[1][n] && vis[n][1]) {
return cout << "0\n", 0;
}
int ans = INF;
int cnt = 0;
for(const auto &[u, v, c, d] : edges) {
if((can[u][1] && can[1][u]) && (can[v][n] && can[n][v]))
cnt++;
else if((can[u][n] && can[n][u]) && (can[v][1] && can[1][v]))
cnt++;
else {
if(can[1][n] && can[n][v] && can[u][1])
ans = min(ans, d);
if(can[n][1] && can[1][v] && can[u][n])
ans = min(ans, d);
}
}
if(cnt == 1) {
for(const auto &[u, v, c, d] : edges) {
if((can[u][1] && can[1][u]) && (can[v][n] && can[n][v]))
continue;
else if((can[u][n] && can[n][u]) && (can[v][1] && can[1][v]))
continue;
if(can[1][n] && (!can[1][u] || !can[u][1]) && can[1][u] && can[v][n])
cnt = INF;
if(can[n][1] && (!can[u][n] || !can[n][u]) && can[n][u] && can[v][1])
cnt = INF;
}
}
if(cnt > 1) {
for(const auto &[u, v, c, d] : edges) {
if((can[u][1] && can[1][u]) && (can[v][n] && can[n][v]))
ans = min(ans, d);
else if((can[u][n] && can[n][u]) && (can[v][1] && can[1][v]))
ans = min(ans, d);
}
}
if(ans == INF || (!can[1][n] && !can[n][1]))
cout << "-1\n";
else
cout << ans << '\n';
}