結果
| 問題 |
No.1976 Cut then Connect
|
| コンテスト | |
| ユーザー |
 Nachia
|
| 提出日時 | 2022-06-10 22:47:15 |
| 言語 | C++17(gcc12) (gcc 12.3.0 + boost 1.87.0) |
| 結果 |
WA
|
| 実行時間 | - |
| コード長 | 6,701 bytes |
| コンパイル時間 | 3,484 ms |
| コンパイル使用メモリ | 131,044 KB |
| 最終ジャッジ日時 | 2025-01-29 20:10:57 |
|
ジャッジサーバーID （参考情報） |
judge1 / judge2 |
（要ログイン）
| ファイルパターン | 結果 |
|---|---|
| sample | AC * 2 |
| other | AC * 13 WA * 18 |
ソースコード
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
#include <atcoder/modint>
#include <utility>
namespace nachia{
struct AdjacencyList{
public:
struct AdjacencyListRange{
using iterator = typename std::vector<int>::const_iterator;
iterator begi, endi;
iterator begin() const { return begi; }
iterator end() const { return endi; }
int size() const { return (int)std::distance(begi, endi); }
const int& operator[](int i) const { return begi[i]; }
};
private:
int mn;
std::vector<int> E;
std::vector<int> I;
public:
AdjacencyList(int n, std::vector<std::pair<int,int>> edges, bool rev){
mn = n;
std::vector<int> buf(n+1, 0);
for(auto [u,v] : edges){ ++buf[u]; if(rev) ++buf[v]; }
for(int i=1; i<=n; i++) buf[i] += buf[i-1];
E.resize(buf[n]);
for(int i=(int)edges.size()-1; i>=0; i--){
auto [u,v] = edges[i];
E[--buf[u]] = v;
if(rev) E[--buf[v]] = u;
}
I = std::move(buf);
}
AdjacencyList(const std::vector<std::vector<int>>& edges = {}){
int n = mn = edges.size();
std::vector<int> buf(n+1, 0);
for(int i=0; i<n; i++) buf[i+1] = buf[i] + edges[i].size();
E.resize(buf[n]);
for(int i=0; i<n; i++) for(int j=0; j<(int)edges[i].size(); j++) E[buf[i]+j] = edges[i][j];
I = std::move(buf);
}
static AdjacencyList from_raw(std::vector<int> targets, std::vector<int> bounds){
AdjacencyList res;
res.mn = bounds.size() - 1;
res.E = std::move(targets);
res.I = std::move(bounds);
return res;
}
AdjacencyListRange operator[](int u) const {
return AdjacencyListRange{ E.begin() + I[u], E.begin() + I[u+1] };
}
int num_vertices() const { return mn; }
int size() const { return num_vertices(); }
int num_edges() const { return E.size(); }
AdjacencyList reversed_edges() const {
AdjacencyList res;
int n = res.mn = mn;
std::vector<int> buf(n+1, 0);
for(int v : E) ++buf[v];
for(int i=1; i<=n; i++) buf[i] += buf[i-1];
res.E.resize(buf[n]);
for(int u=0; u<n; u++) for(int v : operator[](u)) res.E[--buf[v]] = u;
res.I = std::move(buf);
return res;
}
};
struct AdjacencyListEdgeIndexed{
public:
struct Edge { int to; int edgeidx; };
struct AdjacencyListRange{
using iterator = typename std::vector<Edge>::const_iterator;
iterator begi, endi;
iterator begin() const { return begi; }
iterator end() const { return endi; }
int size() const { return (int)std::distance(begi, endi); }
const Edge& operator[](int i) const { return begi[i]; }
};
private:
int mn;
std::vector<Edge> E;
std::vector<int> I;
public:
AdjacencyListEdgeIndexed(int n, const std::vector<std::pair<int,int>>& edges, bool rev){
mn = n;
std::vector<int> buf(n+1, 0);
for(auto [u,v] : edges){ ++buf[u]; if(rev) ++buf[v]; }
for(int i=1; i<=n; i++) buf[i] += buf[i-1];
E.resize(buf[n]);
for(int i=(int)edges.size()-1; i>=0; i--){
auto [u,v] = edges[i];
E[--buf[u]] = { v, i };
if(rev) E[--buf[v]] = { u, i };
}
I = std::move(buf);
}
AdjacencyListEdgeIndexed() : AdjacencyListEdgeIndexed(0, {}, false) {}
AdjacencyListRange operator[](int u) const {
return AdjacencyListRange{ E.begin() + I[u], E.begin() + I[u+1] };
}
int num_vertices() const { return mn; }
int size() const { return num_vertices(); }
int num_edges() const { return E.size(); }
AdjacencyListEdgeIndexed reversed_edges() const {
AdjacencyListEdgeIndexed res;
int n = res.mn = mn;
std::vector<int> buf(n+1, 0);
for(auto [v,i] : E) ++buf[v];
for(int i=1; i<=n; i++) buf[i] += buf[i-1];
res.E.resize(buf[n]);
for(int u=0; u<n; u++) for(auto [v,i] : operator[](u)) res.E[--buf[v]] = {u,i};
res.I = std::move(buf);
return res;
}
};
} // namespace nachia
using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(int)(n); i++)
const i64 INF = 1001001001001001001;
using modint = atcoder::static_modint<1000000007>;
int main(){
int N; cin >> N;
vector<pair<int,int>> edges(N-1);
rep(i,N-1){ int u,v; cin >> u >> v; u--; v--; edges[i] = make_pair(u,v); }
auto adj = nachia::AdjacencyList(N, edges, true);
vector<int> bfs = {0};
vector<int> P(N, -1);
rep(i,N){
int p = bfs[i];
for(int e : adj[p]) if(P[p] != e){
P[e] = p;
bfs.push_back(e);
}
}
vector<int> heightL(N, 0);
vector<int> diamL(N, 0);
for(int i=N-1; i>=0; i--){
int p = bfs[i];
if(i != 0){
diamL[P[p]] = max(diamL[P[p]], heightL[P[p]] + heightL[p] + 1);
diamL[P[p]] = max(diamL[P[p]], diamL[p]);
heightL[P[p]] = max(heightL[P[p]], heightL[p] + 1);
}
}
vector<int> heightH(N, -1);
vector<int> diamH(N, 0);
for(int i=0; i<N; i++){
int p = bfs[i];
int C = adj[p].size();
int cheight = heightH[p];
int cdiam = diamH[p];
for(int ci=0; ci<C; ci++) if(P[p] != adj[p][ci]){
int c = adj[p][ci];
diamH[c] = max(diamH[c], heightH[c] + cheight + 1);
diamH[c] = max(diamH[c], cdiam);
heightH[c] = max(heightH[c], cheight + 1);
cheight = max(cheight, heightL[c]);
cdiam = max(cdiam, diamL[c]);
cdiam = max(cdiam, heightH[c] + cheight + 1);
}
cheight = -1;
cdiam = 0;
for(int ci=C-1; ci>=0; ci--) if(P[p] != adj[p][ci]){
int c = adj[p][ci];
diamH[c] = max(diamH[c], heightH[c] + cheight + 1);
diamH[c] = max(diamH[c], cdiam);
heightH[c] = max(heightH[c], cheight + 1);
cheight = max(cheight, heightL[c]);
cdiam = max(cdiam, diamL[c]);
cdiam = max(cdiam, heightH[c] + cheight + 1);
}
}
int ans = N;
rep(i,N) if(i != 0){
int p = bfs[i];
int cr_ans = (diamL[p] + 1) / 2 + (diamH[p] + 1) / 2 + 1;
cr_ans = max({ cr_ans, diamL[p], diamH[p] });
ans = min(ans, cr_ans);
}
cout << ans << '\n';
return 0;
}
struct ios_do_not_sync{
ios_do_not_sync(){
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
}
} ios_do_not_sync_instance;