160 lines
3.1 KiB
C++
160 lines
3.1 KiB
C++
/* Problem URL: https://codeforces.com/gym/101908/problem/L */
|
|
|
|
#include <bits/stdc++.h>
|
|
|
|
using namespace std;
|
|
|
|
#define V vector
|
|
|
|
#define rmin(a, b) a = min(a, b)
|
|
#define rmax(a, b) a = max(a, b)
|
|
|
|
#define rep(i, lim) for (int i = 0; i < (lim); i++)
|
|
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
|
|
|
|
#define repv(i, v) for (auto &i : (v))
|
|
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
|
|
#define sortv(v) sort(v.begin(), v.end())
|
|
#define all(v) (v).begin(), (v).end()
|
|
|
|
using vi = vector<int>;
|
|
using vvi = vector<vi>;
|
|
using vvvi = vector<vvi>;
|
|
using vvvvi = vector<vvvi>;
|
|
|
|
using ll = long long;
|
|
|
|
using vl = vector<ll>;
|
|
using vvl = vector<vl>;
|
|
using vvvl = vector<vvl>;
|
|
using vvvvl = vector<vvvl>;
|
|
|
|
template<class v>
|
|
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
|
|
os << vec[0];
|
|
for (size_t i = 1; i < vec.size(); i++) {
|
|
os << ' ' << vec[i];
|
|
}
|
|
os << '\n';
|
|
return os;
|
|
}
|
|
|
|
template<class v>
|
|
auto operator>>(istream &is, vector<v> &vec)->istream& {
|
|
for (auto &i : vec) {
|
|
is >> i;
|
|
}
|
|
return is;
|
|
}
|
|
|
|
template<class v>
|
|
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
|
|
for (auto &i : vec) {
|
|
os << i[0];
|
|
for (size_t j = 1; j < i.size(); j++) {
|
|
os << ' ' << i[j];
|
|
}
|
|
os << '\n';
|
|
}
|
|
return os;
|
|
}
|
|
|
|
template<class v>
|
|
auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
|
|
for (auto &i : vec) {
|
|
for (auto &j : i) {
|
|
is >> j;
|
|
}
|
|
}
|
|
return is;
|
|
}
|
|
|
|
int main()
|
|
{
|
|
ios::sync_with_stdio(false);
|
|
cin.tie(nullptr);
|
|
|
|
int n, q;
|
|
cin >> n >> q;
|
|
|
|
vvi graph(n);
|
|
|
|
rep(i, n - 1) {
|
|
int a, b;
|
|
cin >> a >> b;
|
|
a--, b--;
|
|
|
|
graph[a].push_back(b);
|
|
graph[b].push_back(a);
|
|
}
|
|
|
|
vvi parent(n, vi(20, 0));
|
|
vi depth(n, 0);
|
|
|
|
function<void(int, int)> dfs = [&](int i, int p) {
|
|
depth[i] = depth[p] + 1;
|
|
parent[i][0] = p;
|
|
|
|
nrep(j, 1, 20) {
|
|
parent[i][j] = parent[parent[i][j - 1]][j - 1];
|
|
}
|
|
|
|
for (auto j : graph[i]) {
|
|
if (j == p) {
|
|
continue;
|
|
}
|
|
|
|
dfs(j, i);
|
|
}
|
|
};
|
|
|
|
dfs(0, 0);
|
|
|
|
auto lca = [&](int a, int b) {
|
|
if (depth[a] > depth[b]) {
|
|
swap(a, b);
|
|
}
|
|
|
|
int diff = depth[b] - depth[a];
|
|
|
|
rep(i, 20) {
|
|
if ((diff >> i) & 1) {
|
|
b = parent[b][i];
|
|
}
|
|
}
|
|
|
|
if (a == b) {
|
|
return a;
|
|
}
|
|
|
|
for (int i = 19; i >= 0; i--) {
|
|
if (parent[a][i] != parent[b][i]) {
|
|
a = parent[a][i];
|
|
b = parent[b][i];
|
|
}
|
|
}
|
|
|
|
return parent[a][0];
|
|
};
|
|
|
|
auto dis = [&](int a, int b) {
|
|
return depth[a] + depth[b] - 2 * depth[lca(a, b)];
|
|
};
|
|
|
|
while (q--) {
|
|
int a, b, c, d;
|
|
cin >> a >> b >> c >> d;
|
|
a--, b--, c--, d--;
|
|
|
|
int x = dis(a, b) + dis(c, d);
|
|
int y = min(dis(a, c) + dis(b, d), dis(a, d) + dis(b, c));
|
|
|
|
if (y > x) {
|
|
cout << "0\n";
|
|
continue;
|
|
}
|
|
|
|
cout << (x - y) / 2 + 1 << '\n';
|
|
}
|
|
}
|