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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#153231 | #6847. Hide-And-Seek Game | jrjyy# | AC ✓ | 74ms | 3720kb | C++20 | 2.7kb | 2023-08-29 18:24:44 | 2023-08-29 18:24:46 |
Judging History
answer
/* a.cpp */
#include <bits/stdc++.h>
using i64 = long long;
int exgcd(int a, int b, int &x, int &y) {
if (b == 0) {
x = 1;
y = 0;
return a;
}
int g = exgcd(b, a % b, y, x);
y -= a / b * x;
return g;
}
void solve() {
int n, m;
std::cin >> n >> m;
std::vector<std::vector<int>> adj(n);
for (int i = 0; i < n - 1; ++i) {
int u, v;
std::cin >> u >> v;
--u, --v;
adj[u].push_back(v), adj[v].push_back(u);
}
std::vector<int> dep(n), fa(n, -1);
auto dfs = [&](auto self, int u) -> void {
for (auto v : adj[u]) if (v != fa[u]) {
dep[v] = dep[u] + 1;
fa[v] = u;
self(self, v);
}
};
dfs(dfs, 0);
auto apply = [&](auto &f, int s, int t) {
std::fill(f.begin(), f.end(), std::array{-1, -1});
int x = s, y = t, l = 0;
while (x != y) {
if (dep[x] >= dep[y]) {
x = fa[x];
} else {
y = fa[y];
}
l += 1;
}
int p = 0, q = 0;
while (s != t) {
if (dep[s] >= dep[t]) {
f[s] = {p, 2 * l - p};
s = fa[s];
p += 1;
} else {
f[t] = {l - q, l + q};
t = fa[t];
q += 1;
}
}
f[s] = {p, 2 * l - p};
return 2 * l;
};
std::vector<std::array<int, 2>> f(n), g(n);
while (m--) {
int sa, ta, sb, tb;
std::cin >> sa >> ta >> sb >> tb;
--sa, --ta, --sb, --tb;
int la = apply(f, sa, ta), lb = apply(g, sb, tb);
int x, y, z = exgcd(la, lb, x, y);
std::pair<int, int> ans{1e9, -2};
for (int i = 0; i < n; ++i) {
if (f[i][0] == -1 || g[i][0] == -1) {
continue;
}
for (auto a : f[i]) {
for (auto b : g[i]) {
a %= la, b %= lb;
if ((a - b) % z) {
continue;
}
int res = (b - a) / z * x % (lb / z) * la + a;
res %= lb / z * la;
if (res < 0) {
res += lb / z * la;
}
ans = std::min(ans, {res, i});
}
}
}
std::cout << ans.second + 1 << '\n';
}
}
int main() {
std::cin.tie(nullptr)->sync_with_stdio(false);
int t;
std::cin >> t;
while (t--) {
solve();
}
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 74ms
memory: 3720kb
input:
500 6 20 1 2 1 3 3 4 2 5 3 6 1 6 6 5 2 1 6 2 5 1 2 6 2 6 1 2 6 3 6 4 4 1 1 3 5 6 3 4 2 1 3 5 2 4 1 2 6 2 1 2 6 2 1 4 1 6 1 6 2 5 2 6 2 5 6 2 5 2 1 3 5 6 6 4 4 1 4 5 5 4 4 1 3 6 1 2 6 1 4 3 71 30 1 2 2 3 2 4 4 5 2 6 6 7 4 8 2 9 1 10 9 11 3 12 5 13 5 14 10 15 6 16 13 17 17 18 4 19 5 20 17 21 20 22 4 2...
output:
3 -1 -1 -1 6 3 -1 1 -1 1 3 1 2 -1 -1 3 4 1 -1 3 -1 11 2 -1 5 -1 17 -1 -1 5 -1 -1 -1 -1 2 -1 5 53 5 7 -1 -1 2 4 -1 -1 -1 -1 -1 -1 -1 5 -1 1 5 1 -1 -1 -1 -1 33 5 1 1 -1 1 -1 -1 -1 -1 7 -1 -1 9 5 3 -1 -1 -1 19 -1 -1 6 5 -1 -1 5 -1 -1 -1 -1 1 -1 7 -1 -1 1 -1 -1 -1 8 -1 13 -1 -1 -1 -1 4 5 -1 -1 5 -1 -1 8...
result:
ok 53199 lines