結果

問題 No.2337 Equidistant
ユーザー t98slider
提出日時 2023-06-02 23:29:02
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 5,670 bytes
コンパイル時間 2,401 ms
コンパイル使用メモリ 188,144 KB
実行使用メモリ 123,548 KB
最終ジャッジ日時 2024-12-28 23:00:41
合計ジャッジ時間 15,010 ms
ジャッジサーバーID
(参考情報)
judge2 / judge1
このコードへのチャレンジ
(要ログイン)
ファイルパターン 結果
sample AC * 1
other AC * 2 WA * 26
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct ReRooting{
using T = int;
const T identity = 0; //merge
int n;
vector<vector<int>> G;
vector<vector<T>> dp;
vector<vector<T>> dp2;
vector<T> ans;
//viR
T receive(int v, int i, T &R){
return T(R);
}
//lreceivemerge
//merge
T merge(T l, T r){
return l + r;
}
//
T givep(int v, T cum){
return cum + 1;
}
ReRooting() {}
ReRooting(int N):n(N){
G.resize(N);
dp.resize(N);
dp2.resize(N);
ans.resize(N,identity);
}
void add_edge(int a, int b) {
G[a].emplace_back(b);
G[b].emplace_back(a);
}
void read(){
int a, b;
for(int i = 1; i < n; i++){
cin >> a >> b;
a--, b--;
G[a].emplace_back(b);
G[b].emplace_back(a);
}
}
void build() {
for(int i = 0; i < n; i++){
sort(G[i].begin(), G[i].end());
}
dfs(0); // DP
dfs2(0, identity); // DP
}
T dfs(int v, int p = -1) {
T res = identity;
int deg = G[v].size();
dp[v] = vector<T>(deg, identity);
for (int i = 0; i < deg; i++) {
int u = G[v][i];
if (u == p) continue;
dp[v][i] = dfs(u, v);
res = merge(res, receive(v, i, dp[v][i]) );
}
return givep(v,res);
}
void dfs2(int v, const T& dp_p, int p = -1) {
int deg = G[v].size();
for (int i = 0; i < deg; i++) { // dfsDP
if (G[v][i] == p){dp[v][i] = dp_p; break;}
}
vector<T> dp_l(deg + 1, identity), dp_r(deg + 1, identity); // merge
for (int i = 0; i < deg; i++) {
dp_l[i + 1] = merge(dp_l[i], receive(v, i, dp[v][i]));
}
dp2[v] = dp_l;
for (int i = deg - 1; i >= 0; i--) {
dp_r[i] = merge(dp_r[i + 1], receive(v, i, dp[v][i]));
}
ans[v] = dp_l[deg]; // v
for (int i = 0; i < deg; i++) { //
int u = G[v][i];
if (u == p) continue;
dfs2(u, givep(v,merge(dp_l[i], dp_r[i + 1])),v);
}
}
};
struct LCA_tree{
int _n,MAX_LOG_V,root;
vector<vector<int>> g;
vector<vector<int>> parent;
vector<int> depth;
LCA_tree() : _n(0) {}
LCA_tree(int n) : _n(n), g(n),depth(n) {
MAX_LOG_V = 1;
while(_n >> MAX_LOG_V) MAX_LOG_V++;
parent.resize(MAX_LOG_V, vector<int>(_n));
}
void merge(int u, int v){
g[u].push_back(v);
g[v].push_back(u);
}
void dfs(int v,int p,int d){
parent[0][v]=p;
depth[v]=d;
for(int i=0;i<g[v].size();i++){
if(g[v][i]!=p)dfs(g[v][i],v,d+1);
}
}
void init(int r){
root=r;
dfs(root,-1,0);
for(int j=0;j+1<MAX_LOG_V;j++){
for(int i=0;i<_n;i++){
if(parent[j][i]<0)parent[j+1][i]=-1;
else parent[j+1][i]=parent[j][parent[j][i]];
}
}
}
int lca(int u,int v){
if(depth[u]>depth[v])swap(u,v);
for(int i=0;i<MAX_LOG_V;i++){
if((depth[v]-depth[u])>>i&1)v=parent[i][v];
}
if(u==v)return u;
for(int i=MAX_LOG_V-1;i>=0;i--){
if(parent[i][u]!=parent[i][v]){
u=parent[i][u];
v=parent[i][v];
}
}
return parent[0][u];
}
//
int dist(int u,int v){
int lcav=lca(u,v);
if(lcav==-1)return depth[u]+depth[v];
return depth[u]+depth[v]-2*depth[lcav];
}
int la(int v, int k){
for(int j = MAX_LOG_V - 1; j >= 0; j--){
if(k >> j & 1){
v = parent[j][v];
}
}
return v;
}
array<int, 3> pos(int u, int v){
int lcav = lca(u, v);
int dv = depth[u] + depth[v] - 2 * depth[lcav];
if(dv & 1) return array<int,3>({-1, -1, -1});
dv /= 2;
if(dv == depth[lcav] - depth[v]){
return array<int,3>({lcav, la(v, dv - 1), la(u, dv - 1)});
}
if(depth[lcav] - depth[v] < dv) swap(v, u);
return array<int,3>({la(v, dv), la(v, dv - 1), la(v, dv + 1)});
}
//wu,v
int on_path(int u,int v,int w){
return (dist(u,w)+dist(v,w)==dist(u,v));
}
};
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int n, q;
cin >> n >> q;
vector<vector<int>> g(n);
for(int i = 1; i < n; i++){
int u, v;
cin >> u >> v;
g[--u].emplace_back(--v);
g[v].emplace_back(u);
}
LCA_tree G1(n);
ReRooting G2(n);
G1.g = g;
G2.G = g;
G1.init(0);
G2.build();
auto f = [&](int v, int u){
int j = lower_bound(G2.G[v].begin(), G2.G[v].end(), u) - G2.G[v].begin();
return G2.dp[v][j];
};
while(q--){
int u, v;
cin >> u >> v;
u--, v--;
auto b = G1.pos(u, v);
if(b[0] == -1){
cout << 0 << '\n';
continue;
}
int ans = n;
ans -= f(b[0], b[1]) + f(b[0], b[2]);
cout << ans << '\n';
}
}
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