結果

問題 No.1976 Cut then Connect
ユーザー 👑 NachiaNachia
提出日時 2023-02-19 05:48:03
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 28 ms / 2,000 ms
コード長 14,004 bytes
コンパイル時間 1,121 ms
コンパイル使用メモリ 88,888 KB
最終ジャッジ日時 2025-02-10 19:03:24
ジャッジサーバーID
(参考情報)
judge4 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 31
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ソースコード

diff #
プレゼンテーションモードにする

#line 2 "nachia\\graph\\graph.hpp"
#include <vector>
#include <utility>
#include <cassert>
#line 4 "nachia\\array\\csr-array.hpp"
#include <algorithm>
namespace nachia{
template<class Elem>
class CsrArray{
public:
struct ListRange{
using iterator = typename std::vector<Elem>::iterator;
iterator begi, endi;
iterator begin() const { return begi; }
iterator end() const { return endi; }
int size() const { return (int)std::distance(begi, endi); }
Elem& operator[](int i) const { return begi[i]; }
};
struct ConstListRange{
using iterator = typename std::vector<Elem>::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 Elem& operator[](int i) const { return begi[i]; }
};
private:
int m_n;
std::vector<Elem> m_list;
std::vector<int> m_pos;
public:
CsrArray() : m_n(0), m_list(), m_pos() {}
static CsrArray Construct(int n, std::vector<std::pair<int, Elem>> items){
CsrArray res;
res.m_n = n;
std::vector<int> buf(n+1, 0);
for(auto& [u,v] : items){ ++buf[u]; }
for(int i=1; i<=n; i++) buf[i] += buf[i-1];
res.m_list.resize(buf[n]);
for(int i=(int)items.size()-1; i>=0; i--){
res.m_list[--buf[items[i].first]] = std::move(items[i].second);
}
res.m_pos = std::move(buf);
return res;
}
static CsrArray FromRaw(std::vector<Elem> list, std::vector<int> pos){
CsrArray res;
res.m_n = pos.size() - 1;
res.m_list = std::move(list);
res.m_pos = std::move(pos);
return res;
}
ListRange operator[](int u) { return ListRange{ m_list.begin() + m_pos[u], m_list.begin() + m_pos[u+1] }; }
ConstListRange operator[](int u) const { return ConstListRange{ m_list.begin() + m_pos[u], m_list.begin() + m_pos[u+1] }; }
int size() const { return m_n; }
int fullSize() const { return (int)m_list.size(); }
};
} // namespace nachia
#line 6 "nachia\\graph\\graph.hpp"
namespace nachia{
struct Graph {
public:
struct Edge{
int from, to;
void reverse(){ std::swap(from, to); }
};
using Base = std::vector<std::pair<int, int>>;
Graph(int n = 0, bool undirected = false) : m_n(n), m_e(), m_isUndir(undirected) {}
Graph(int n, const std::vector<std::pair<int, int>>& edges, bool undirected = false) : m_n(n), m_isUndir(undirected){
m_e.resize(edges.size());
for(std::size_t i=0; i<edges.size(); i++) m_e[i] = { edges[i].first, edges[i].second };
}
Graph(int n, const std::vector<Edge>& edges, bool undirected = false) : m_n(n), m_e(edges), m_isUndir(undirected) {}
Graph(int n, std::vector<Edge>&& edges, bool undirected = false) : m_n(n), m_e(std::move(edges)), m_isUndir(undirected) {}
int numVertices() const noexcept { return m_n; }
int numEdges() const noexcept { return int(m_e.size()); }
int addNode() noexcept { return m_n++; }
int addEdge(int from, int to){ m_e.push_back({ from, to }); return numEdges() - 1; }
Edge& operator[](int ei) noexcept { return m_e[ei]; }
const Edge& operator[](int ei) const noexcept { return m_e[ei]; }
Edge& at(int ei) { return m_e.at(ei); }
const Edge& at(int ei) const { return m_e.at(ei); }
auto begin(){ return m_e.begin(); }
auto end(){ return m_e.end(); }
auto begin() const { return m_e.begin(); }
auto end() const { return m_e.end(); }
bool isUndirected() const noexcept { return m_isUndir; }
void reverseEdges() noexcept { for(auto& e : m_e) e.reverse(); }
void contract(int newV, const std::vector<int>& mapping){
assert(numVertices() == int(mapping.size()));
for(int i=0; i<numVertices(); i++) assert(0 <= mapping[i] && mapping[i] < newV);
for(auto& e : m_e){ e.from = mapping[e.from]; e.to = mapping[e.to]; }
}
std::vector<Graph> induce(int num, const std::vector<int>& mapping) const {
int n = numVertices();
assert(n == int(mapping.size()));
for(int i=0; i<n; i++) assert(-1 <= mapping[i] && mapping[i] < num);
std::vector<int> indexV(n), newV(num);
for(int i=0; i<n; i++) if(mapping[i] >= 0) indexV[i] = newV[mapping[i]]++;
std::vector<Graph> res; res.reserve(num);
for(int i=0; i<num; i++) res.emplace_back(newV[i], isUndirected());
for(auto e : m_e) if(mapping[e.from] == mapping[e.to] && mapping[e.to] >= 0) res[mapping[e.to]].addEdge(indexV[e.from], indexV[e.to]);
return res;
}
CsrArray<int> getEdgeIndexArray(bool undirected) const {
std::vector<std::pair<int, int>> src;
src.reserve(numEdges() * (undirected ? 2 : 1));
for(int i=0; i<numEdges(); i++){
auto e = operator[](i);
src.emplace_back(e.from, i);
if(undirected) src.emplace_back(e.to, i);
}
return CsrArray<int>::Construct(numVertices(), src);
}
CsrArray<int> getEdgeIndexArray() const { return getEdgeIndexArray(isUndirected()); }
CsrArray<int> getAdjacencyArray(bool undirected) const {
std::vector<std::pair<int, int>> src;
src.reserve(numEdges() * (undirected ? 2 : 1));
for(auto e : m_e){
src.emplace_back(e.from, e.to);
if(undirected) src.emplace_back(e.to, e.from);
}
return CsrArray<int>::Construct(numVertices(), src);
}
CsrArray<int> getAdjacencyArray() const { return getAdjacencyArray(isUndirected()); }
private:
int m_n;
std::vector<Edge> m_e;
bool m_isUndir;
};
} // namespace nachia
#line 5 "nachia\\tree\\any-direction-tree-dp.hpp"
namespace nachia{
struct S {
int height = 0;
int diam = 0;
};
S rake(S l, S r){
S res;
res.height = std::max(l.height, r.height);
res.diam = std::max({ l.diam, r.diam, l.height + r.height });
return res;
}
S compress(S l, int egdeIdx, int nodeIdx){
S res;
res.height = l.height + 1;
res.diam = std::max(l.diam, res.height);
return res;
}
struct AnyDirectionTreeDP{
std::vector<S> low;
std::vector<S> high;
std::vector<int> XorEdge;
std::vector<int> P;
AnyDirectionTreeDP(const Graph& tree, std::vector<S> node){
int n = tree.numVertices();
auto adj = tree.getEdgeIndexArray(true);
XorEdge.resize(n-1);
for(int i=0; i<n-1; i++) XorEdge[i] = tree[i].from ^ tree[i].to;
std::vector<int> bfs = {0};
bfs.reserve(n);
P.assign(n, -1);
for(int i=0; i<n; i++){
int v = bfs[i];
for(int e : adj[v]){
int w = v ^ XorEdge[e];
if(P[v] != e){ P[w] = e; bfs.push_back(w); }
}
}
low = node;
for(int i=n-1; i>=1; i--){
int w = bfs[i];
int v = w ^ XorEdge[P[w]];
low[v] = rake(low[v], compress(low[w], P[v], v));
}
high = node;
for(int i=0; i<n; i++){
int v = bfs[i];
int C = adj[v].size();
S fold = i ? compress(high[v], P[v], v ^ XorEdge[v]) : high[v];
for(int ci=C-1; ci>=0; ci--){
int e = adj[v][ci];
if(P[v] == e) continue;
int w = v ^ XorEdge[e];
high[w] = fold;
fold = rake(fold, compress(low[w], e, v));
}
fold = node[v];
for(int ci=0; ci<C; ci++){
int e = adj[v][ci];
if(P[v] == e) continue;
int w = v ^ XorEdge[e];
high[w] = rake(high[w], fold);
fold = rake(fold, compress(low[w], e, v));
}
}
}
S getAtVtx(int i){
if(i == 0) return low[i];
return rake(compress(high[i], P[i], i), low[i]);
}
S getAtEdge(int root, int edge){
if(P[root] == edge) return low[root];
return high[root ^ XorEdge[edge]];
}
};
} // namespace nachia
#line 2 "nachia\\misc\\fastio.hpp"
#include <cstdio>
#include <cctype>
#include <cstdint>
#include <string>
namespace nachia{
struct CInStream{
private:
static const unsigned int INPUT_BUF_SIZE = 1 << 17;
unsigned int p = INPUT_BUF_SIZE;
static char Q[INPUT_BUF_SIZE];
public:
using MyType = CInStream;
char seekChar() noexcept {
if(p == INPUT_BUF_SIZE){
size_t len = fread(Q, 1, INPUT_BUF_SIZE, stdin);
if(len != INPUT_BUF_SIZE) Q[len] = '\0';
p = 0;
}
return Q[p];
}
void skipSpace() noexcept { while(isspace(seekChar())) p++; }
uint32_t nextU32() noexcept {
skipSpace();
uint32_t buf = 0;
while(true){
char tmp = seekChar();
if('9' < tmp || tmp < '0') break;
buf = buf * 10 + (tmp - '0');
p++;
}
return buf;
}
int32_t nextI32() noexcept {
skipSpace();
if(seekChar() == '-'){ p++; return (int32_t)(-nextU32()); }
return (int32_t)nextU32();
}
uint64_t nextU64() noexcept {
skipSpace();
uint64_t buf = 0;
while(true){
char tmp = seekChar();
if('9' < tmp || tmp < '0') break;
buf = buf * 10 + (tmp - '0');
p++;
}
return buf;
}
int64_t nextI64() noexcept {
skipSpace();
if(seekChar() == '-'){ p++; return (int64_t)(-nextU64()); }
return (int64_t)nextU64();
}
char nextChar() noexcept { skipSpace(); char buf = seekChar(); p++; return buf; }
std::string nextToken(){
skipSpace();
std::string buf;
while(true){
char ch = seekChar();
if(isspace(ch) || ch == '\0') break;
buf.push_back(ch);
p++;
}
return buf;
}
MyType& operator>>(unsigned int& dest) noexcept { dest = nextU32(); return *this; }
MyType& operator>>(int& dest) noexcept { dest = nextI32(); return *this; }
MyType& operator>>(unsigned long& dest) noexcept { dest = nextU64(); return *this; }
MyType& operator>>(long& dest) noexcept { dest = nextI64(); return *this; }
MyType& operator>>(unsigned long long& dest) noexcept { dest = nextU64(); return *this; }
MyType& operator>>(long long& dest) noexcept { dest = nextI64(); return *this; }
MyType& operator>>(std::string& dest){ dest = nextToken(); return *this; }
MyType& operator>>(char& dest) noexcept { dest = nextChar(); return *this; }
} cin;
struct FastOutputTable{
char LZ[1000][4] = {};
char NLZ[1000][4] = {};
constexpr FastOutputTable(){
using u32 = uint_fast32_t;
for(u32 d=0; d<1000; d++){
LZ[d][0] = ('0' + d / 100 % 10);
LZ[d][1] = ('0' + d / 10 % 10);
LZ[d][2] = ('0' + d / 1 % 10);
LZ[d][3] = '\0';
}
for(u32 d=0; d<1000; d++){
u32 i = 0;
if(d >= 100) NLZ[d][i++] = ('0' + d / 100 % 10);
if(d >= 10) NLZ[d][i++] = ('0' + d / 10 % 10);
if(d >= 1) NLZ[d][i++] = ('0' + d / 1 % 10);
NLZ[d][i++] = '\0';
}
}
};
struct COutStream{
private:
using u32 = uint32_t;
using u64 = uint64_t;
using MyType = COutStream;
static const u32 OUTPUT_BUF_SIZE = 1 << 17;
static char Q[OUTPUT_BUF_SIZE];
static constexpr FastOutputTable TB = FastOutputTable();
u32 p = 0;
static constexpr u32 P10(u32 d){ return d ? P10(d-1)*10 : 1; }
static constexpr u64 P10L(u32 d){ return d ? P10L(d-1)*10 : 1; }
template<class T, class U> static void Fil(T& m, U& l, U x) noexcept { m = l/x; l -= m*x; }
void next_dig9(u32 x){
u32 y;
Fil(y, x, P10(6));
nextCstr(TB.LZ[y]);
Fil(y, x, P10(3));
nextCstr(TB.LZ[y]); nextCstr(TB.LZ[x]);
}
public:
void nextChar(char c){
Q[p++] = c;
if(p == OUTPUT_BUF_SIZE){ fwrite(Q, p, 1, stdout); p = 0; }
}
void nextEoln(){ nextChar('\n'); }
void nextCstr(const char* s){ while(*s) nextChar(*(s++)); }
void nextU32(uint32_t x){
u32 y = 0;
if(x >= P10(9)){
Fil(y, x, P10(9));
nextCstr(TB.NLZ[y]); next_dig9(x);
}
else if(x >= P10(6)){
Fil(y, x, P10(6));
nextCstr(TB.NLZ[y]);
Fil(y, x, P10(3));
nextCstr(TB.LZ[y]); nextCstr(TB.LZ[x]);
}
else if(x >= P10(3)){
Fil(y, x, P10(3));
nextCstr(TB.NLZ[y]); nextCstr(TB.LZ[x]);
}
else if(x >= 1) nextCstr(TB.NLZ[x]);
else nextChar('0');
}
void nextI32(int32_t x){
if(x >= 0) nextU32(x);
else{ nextChar('-'); nextU32((u32)-x); }
}
void nextU64(uint64_t x){
u32 y = 0;
if(x >= P10L(18)){
Fil(y, x, P10L(18));
nextU32(y);
Fil(y, x, P10L(9));
next_dig9(y); next_dig9(x);
}
else if(x >= P10L(9)){
Fil(y, x, P10L(9));
nextU32(y); next_dig9(x);
}
else nextU32(x);
}
void nextI64(int64_t x){
if(x >= 0) nextU64(x);
else{ nextChar('-'); nextU64((u64)-x); }
}
void writeToFile(bool flush = false){
fwrite(Q, p, 1, stdout);
if(flush) fflush(stdout);
p = 0;
}
COutStream(){ Q[0] = 0; }
~COutStream(){ writeToFile(); }
MyType& operator<<(unsigned int tg){ nextU32(tg); return *this; }
MyType& operator<<(unsigned long tg){ nextU64(tg); return *this; }
MyType& operator<<(unsigned long long tg){ nextU64(tg); return *this; }
MyType& operator<<(int tg){ nextI32(tg); return *this; }
MyType& operator<<(long tg){ nextI64(tg); return *this; }
MyType& operator<<(long long tg){ nextI64(tg); return *this; }
MyType& operator<<(const std::string& tg){ nextCstr(tg.c_str()); return *this; }
MyType& operator<<(const char* tg){ nextCstr(tg); return *this; }
MyType& operator<<(char tg){ nextChar(tg); return *this; }
} cout;
char CInStream::Q[INPUT_BUF_SIZE];
char COutStream::Q[OUTPUT_BUF_SIZE];
} // namespace nachia
#line 4 "Main.cpp"
int main(){
using nachia::cin, nachia::cout;
int N; cin >> N;
nachia::Graph tree(N, true);
for(int i=0; i<N-1; i++){
int u, v; cin >> u >> v; u--; v--;
tree.addEdge(u, v);
}
auto treedp = nachia::AnyDirectionTreeDP(tree, std::vector<nachia::S>(N));
int ans = N;
for(int e=0; e<N-1; e++){
int diam1 = treedp.getAtEdge(tree[e].from, e).diam;
int diam2 = treedp.getAtEdge(tree[e].to, e).diam;
int cr_ans = (diam1 + 1) / 2 + (diam2 + 1) / 2 + 1;
cr_ans = std::max({ cr_ans, diam1, diam2 });
ans = std::min(ans, cr_ans);
}
cout << ans << '\n';
return 0;
}
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