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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#562996 | #8941. Even or Odd Spanning Tree | ucup-team3519 | WA | 0ms | 7732kb | C++20 | 3.7kb | 2024-09-14 00:02:11 | 2024-09-14 00:02:18 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
const int LOGN = 20;
struct Edge {
int u, v;
int64_t w;
bool in_mst;
};
int T, n, m;
int parent[MAXN][LOGN], depth[MAXN];
int64_t max_edge[MAXN][LOGN];
vector<pair<int, int64_t>> tree[MAXN];
vector<Edge> edges;
int find_set(vector<int>& dsuf, int u) {
if (dsuf[u] != u)
dsuf[u] = find_set(dsuf, dsuf[u]);
return dsuf[u];
}
void union_sets(vector<int>& dsuf, int u, int v) {
u = find_set(dsuf, u);
v = find_set(dsuf, v);
if (u != v)
dsuf[u] = v;
}
void dfs(int u, int p, int64_t w) {
parent[u][0] = p;
max_edge[u][0] = w;
depth[u] = depth[p] + 1;
for (int k = 1; k < LOGN; ++k) {
parent[u][k] = parent[parent[u][k - 1]][k - 1];
max_edge[u][k] = max(max_edge[u][k - 1], max_edge[parent[u][k - 1]][k - 1]);
}
for (auto& [v, weight] : tree[u]) {
if (v != p) {
dfs(v, u, weight);
}
}
}
int64_t query_max(int u, int v) {
if (depth[u] < depth[v])
swap(u, v);
int64_t res = 0;
for (int k = LOGN - 1; k >= 0; --k) {
if (depth[parent[u][k]] >= depth[v]) {
res = max(res, max_edge[u][k]);
u = parent[u][k];
}
}
if (u == v)
return res;
for (int k = LOGN - 1; k >= 0; --k) {
if (parent[u][k] != parent[v][k]) {
res = max({res, max_edge[u][k], max_edge[v][k]});
u = parent[u][k];
v = parent[v][k];
}
}
res = max({res, max_edge[u][0], max_edge[v][0]});
return res;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> T;
while (T--) {
cin >> n >> m;
edges.clear();
for (int i = 0; i <= n; ++i)
tree[i].clear();
for (int i = 0; i < m; ++i) {
int u, v;
int64_t w;
cin >> u >> v >> w;
edges.push_back({u, v, w, false});
}
// Kruskal's algorithm to build MST
vector<int> dsuf(n + 1);
iota(dsuf.begin(), dsuf.end(), 0);
sort(edges.begin(), edges.end(), [](const Edge& a, const Edge& b) {
return a.w < b.w;
});
int64_t cost_mst = 0;
for (auto& e : edges) {
int u = find_set(dsuf, e.u);
int v = find_set(dsuf, e.v);
if (u != v) {
union_sets(dsuf, u, v);
e.in_mst = true;
cost_mst += e.w;
tree[e.u].emplace_back(e.v, e.w);
tree[e.v].emplace_back(e.u, e.w);
}
}
// Initialize LCA structures
depth[0] = -1;
dfs(1, 0, 0);
int64_t min_delta_odd = INT64_MAX;
int64_t min_delta_even = INT64_MAX;
for (auto& e : edges) {
if (!e.in_mst) {
int64_t max_w = query_max(e.u, e.v);
int64_t delta = e.w - max_w;
if (delta < 0)
continue; // Not possible
if (delta % 2 == 1) {
min_delta_odd = min(min_delta_odd, delta);
} else {
min_delta_even = min(min_delta_even, delta);
}
}
}
int64_t T1 = -1, T2 = -1;
if (cost_mst % 2 == 0) {
T1 = cost_mst;
if (min_delta_odd != INT64_MAX) {
T2 = cost_mst + min_delta_odd;
}
} else {
T2 = cost_mst;
if (min_delta_odd != INT64_MAX) {
T1 = cost_mst + min_delta_odd;
}
}
cout << T1 << ' ' << T2 << '\n';
}
return 0;
}
Details
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Test #1:
score: 0
Wrong Answer
time: 0ms
memory: 7732kb
input:
3 2 1 1 2 5 3 1 1 3 1 4 4 1 2 1 1 3 1 1 4 1 2 4 2
output:
-1 5 -1 1 4 3
result:
wrong answer 4th numbers differ - expected: '-1', found: '1'