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QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#273162 | #7883. Takeout Delivering | ucup-team133# | WA | 180ms | 41996kb | C++23 | 4.6kb | 2023-12-02 21:43:30 | 2023-12-02 21:43:30 |
Judging History
answer
#include <bits/stdc++.h>
#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void(0)
#endif
struct UnionFind {
UnionFind(int n) : n(n), num(n), data(n, -1) {}
int find(int x) {
assert(0 <= x && x < n);
return data[x] < 0 ? x : data[x] = find(data[x]);
}
bool merge(int x, int y) {
assert(0 <= x && x < n);
assert(0 <= y && y < n);
if ((x = find(x)) == (y = find(y))) return false;
if (-data[x] < -data[y]) std::swap(x, y);
data[x] += data[y];
data[y] = x;
num--;
return true;
}
bool same(int x, int y) {
assert(0 <= x && x < n);
assert(0 <= y && y < n);
return find(x) == find(y);
}
int size(int x) {
assert(0 <= x && x < n);
return -data[find(x)];
}
int count() const { return num; }
std::vector<std::vector<int>> groups() {
std::vector<std::vector<int>> res(n);
for (int i = 0; i < n; i++) res[find(i)].emplace_back(i);
res.erase(std::remove_if(res.begin(), res.end(), [&](const std::vector<int>& v) { return v.empty(); }));
return res;
}
int operator[](int x) { return find(x); }
private:
int n, num;
// root node : -1 * component size
// otherwise : parent
std::vector<int> data;
};
using namespace std;
typedef long long ll;
#define all(x) begin(x), end(x)
constexpr int INF = (1 << 30) - 1;
constexpr long long IINF = (1LL << 60) - 1;
constexpr int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
template <class T> istream& operator>>(istream& is, vector<T>& v) {
for (auto& x : v) is >> x;
return is;
}
template <class T> ostream& operator<<(ostream& os, const vector<T>& v) {
auto sep = "";
for (const auto& x : v) os << exchange(sep, " ") << x;
return os;
}
template <class T, class U = T> bool chmin(T& x, U&& y) { return y < x and (x = forward<U>(y), true); }
template <class T, class U = T> bool chmax(T& x, U&& y) { return x < y and (x = forward<U>(y), true); }
template <class T> void mkuni(vector<T>& v) {
sort(begin(v), end(v));
v.erase(unique(begin(v), end(v)), end(v));
}
template <class T> int lwb(const vector<T>& v, const T& x) { return lower_bound(begin(v), end(v), x) - begin(v); }
struct edge {
int u, v, w;
edge(int u, int v, int w) : u(u), v(v), w(w) {}
bool operator<(const edge& rhs) const { return w < rhs.w; }
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
cin >> n >> m;
vector<edge> es;
for (int i = 0; i < m; i++) {
int u, v, w;
cin >> u >> v >> w;
es.emplace_back(--u, --v, w);
}
sort(begin(es), end(es));
UnionFind UF(n);
int border = -1, threshold = -1;
vector<vector<pair<int, int>>> G(n);
for (int i = 0; i < m; i++) {
auto [u, v, w] = es[i];
UF.merge(u, v);
G[u].emplace_back(v, w);
G[v].emplace_back(u, w);
if (UF.same(0, n - 1)) {
border = i + 1;
threshold = w;
break;
}
}
assert(border != -1);
ll ans = IINF;
{
vector dp(n, vector<int>(2, INF));
priority_queue<tuple<int, int, int>> pq;
dp[0][0] = 0;
pq.emplace(-dp[0][0], 0, 0);
while (not pq.empty()) {
auto [cost, v, x] = pq.top();
pq.pop();
cost *= -1;
if (dp[v][x] != cost) continue;
for (auto [u, w] : G[v]) {
int nx = x, ncost = cost;
if (x == 0 and w == threshold) {
nx++;
} else
chmax(cost, w);
if (chmin(dp[u][nx], ncost)) pq.emplace(-dp[u][nx], u, nx);
}
}
ans = dp[n - 1][1] + threshold;
}
{
auto calc = [&](int s) -> vector<int> {
vector<int> dp(n, INF);
priority_queue<pair<int, int>> pq;
dp[s] = 0;
pq.emplace(-dp[s], s);
while (not pq.empty()) {
auto [cost, v] = pq.top();
pq.pop();
cost *= -1;
if (dp[v] != cost) continue;
for (auto [u, w] : G[v]) {
if (chmin(dp[u], max(cost, w))) pq.emplace(-dp[u], u);
}
}
return dp;
};
auto dp1 = calc(0), dp2 = calc(n - 1);
for (int i = border; i < m; i++) {
auto [u, v, w] = es[i];
if (dp1[u] == INF) continue;
if (dp2[v] == INF) continue;
chmin(ans, w + max(dp1[u], dp2[v]));
}
}
cout << ans << '\n';
return 0;
}
详细
Test #1:
score: 100
Accepted
time: 1ms
memory: 3524kb
input:
4 6 1 2 2 1 3 4 1 4 7 2 3 1 2 4 3 3 4 9
output:
5
result:
ok 1 number(s): "5"
Test #2:
score: -100
Wrong Answer
time: 180ms
memory: 41996kb
input:
300000 299999 80516 80517 597830404 110190 110191 82173886 218008 218009 954561262 250110 250111 942489774 66540 66541 156425292 34947 34948 239499776 273789 273790 453201232 84428 84429 439418398 98599 98600 326095035 55636 55637 355015760 158611 158612 684292473 43331 43332 43265001 171621 171622 ...
output:
1997532190
result:
wrong answer 1st numbers differ - expected: '1999991697', found: '1997532190'