Submission #838837

#	Time	Username	Problem	Language	Result	Execution time	Memory
838837		Joshua_Andersson	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	368 ms	106652 KiB

catinatree

#undef _GLIBCXX_DEBUG                // disable run-time bound checking, etc
#pragma GCC optimize("Ofast,inline") // Ofast = O3,fast-math,allow-store-data-races,no-protect-parens
#pragma GCC optimize ("unroll-loops")

#pragma GCC target("bmi,bmi2,lzcnt,popcnt")                      // bit manipulation
#pragma GCC target("movbe")                                      // byte swap
#pragma GCC target("aes,pclmul,rdrnd")                           // encryption
#pragma GCC target("avx,avx2,f16c,fma,sse3,ssse3,sse4.1,sse4.2") // SIMD

#include <bits/stdc++.h>
#include <bits/extc++.h>
using namespace std;

#define enablell 1

typedef long long ll;
typedef unsigned long long ull;
#if enablell
#define int ll
#define inf int(1e18)
#else
const int inf = int(2e9);
#endif
typedef vector<ull> vull;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vvvi> vvvvi;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
typedef pair<int, int> p2;
typedef vector<p2> vp2;
typedef vector<vp2> vvp2;
typedef vector<vvp2> vvvp2;
typedef tuple<int, int, int> p3;
typedef vector<p3> vp3;
typedef vector<vp3> vvp3;
typedef vector<vvp3> vvvp3;
typedef tuple<int, int, int, int> p4;
typedef vector<p4> vp4;

#define _LOCAL _MSC_VER > 0
#if _LOCAL

#define assert(x) debassert(x)
#define popcount(x) __popcnt(x)
uint32_t clz(uint32_t x) { return _lzcnt_u32(x); }
uint32_t ctz(uint32_t x) { return _tzcnt_u32(x); }
#define bswap64(x) _byteswap_uint64(x)
#else

#define popcount(x) __builtin_popcountll(x)
uint32_t clz(uint32_t x) { return __builtin_clz(x); }
uint32_t ctz(uint32_t x) { return __builtin_ctzll(x); }
#define bswap64(x) __builtin_bswap64(x)

#if 0
namespace pbds
{
    using namespace __gnu_pbds;

    template<typename T> using indexed_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
    template<typename T, typename U> using indexed_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

    struct chash { // large odd number for C
        const uint64_t C = ll(4e18 * acos(0)) | 71;
        ll operator()(ll x) const { return __builtin_bswap64(x * C); }
    };
    template<typename T, typename U> using fast_map = __gnu_pbds::gp_hash_table<T, U, chash>;
    template<typename T> using fast_set = __gnu_pbds::gp_hash_table<T, null_type, chash>;
    template<typename T, typename H> using fast_set_h = __gnu_pbds::gp_hash_table<T, null_type, H>;
}
using namespace pbds;
#endif
#endif

inline void fast() { ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); }
#define FAST_INPUT 0
#if FAST_INPUT && !_LOCAL
#define gc() getchar_unlocked()
inline void read(int& v) { v = 0; int sign = 1; char c = gc(); if (c == '-') { sign = -1; } else { v += c - '0'; } while ((c = gc()) && c != ' ' && c != '\n') { if (c == EOF) { v = -1; return; } v *= 10; v += c - '0'; } v *= sign; }
inline void read(int& u, int& v) { read(u); read(v); }
inline void read(int& u, int& v, int& k) { read(u); read(v); read(k); }
//inline void read(int& v) { char c; while ((c = getchar()) != EOF && c != ' ' && c != '\n') { v *= 10; v += c - '0'; } }
inline void read(string& s) { char c; while ((c = gc()) != EOF && c != '\n' && c != ' ') { s.push_back(c); } }
inline void readline(string& s) { char c; while ((c = gc()) != EOF && c != '\n') { s.push_back(c); } }
#else
template <typename T> inline void read(T& a) { cin >> a; }
template <typename T> inline void read(T& a, T& b) { cin >> a >> b; }
template <typename T> inline void read(T& a, T& b, T& c) { cin >> a >> b >> c; }
#endif
#define quit cout << endl; _Exit(0);
#define dread(type, a) type a; read(a)
#define dread2(type, a, b) dread(type, a); dread(type, b)
#define dread3(type, a, b, c) dread2(type, a, b); dread(type, c)
#define dread4(type, a, b, c, d) dread3(type, a, b, c); dread(type, d)
#define dread5(type, a, b, c, d, e) dread4(type, a, b, c, d); dread(type, e)
#define readvector(type, name, size) vector<type> name(size); rep(i,size) {dread(type,temp); name[i]=temp;}
#ifdef _DEBUG
#define noop cout << "";
#define deb __debugbreak();
#define debassert(expr) if(!(expr)) deb;
#define debif(expr) if(expr) deb;
void print(const string& s) { cout << s << "\n"; }
#else
#define noop ;
#define deb ;
#define debif(expr) ;
#define debassert(expr) ;
void print(const string& s) {  }
#endif

#define rep(i, high) for (int i = 0; i < high; i++)
#define repp(i, low, high) for (int i = low; i < high; i++)
#define repe(i, container) for (auto& i : container)
#define per(i, high) for (int i = high-1; i >= 0; i--)

#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define setcontains(set, x) (set.find(x) != set.end())
#define sz(container) ((int)container.size())
#define mp(a,b) (make_pair(a,b))

#define ceildiv(x,y) ((x + y - 1) / y)

template <typename T, typename U> inline void operator+=(pair<T, U>& l, const pair<T, U>& r) { l = { l.first + r.first,l.second + r.second }; }
template <typename T, typename U> inline pair<T, U> operator+(const pair<T, U> l, const pair<T, U> r) { return { l.first + r.first, l.second + r.second }; }
template <typename T, typename U> inline pair<T, U> operator-(const pair<T, U> l, const pair<T, U> r) { return { l.first - r.first, l.second - r.second }; }
template <typename T, typename U> inline pair<T, U> operator*(const pair<T, U> l, const int m) { return { l.first * m, l.second * m }; }
template <typename Out> inline void split(const string& s, char delim, Out result) { istringstream iss(s); string item; while (getline(iss, item, delim)) { *result++ = item; } }
inline vector<string> split(const string& s, char delim) { vector<string> elems; split(s, delim, back_inserter(elems)); return elems; }
vector<string> split(string s, string d) { size_t k = 0, n, e = d.length(); string t; vector<string> r; while ((n = s.find(d, k)) != string::npos) { t = s.substr(k, n - k); k = n + e; r.push_back(t); } r.push_back(s.substr(k)); return r; }
ll binpow(ll a, ll b) { ll res = 1; while (b > 0) { if (b & 1) res = res * a; a = a * a; b >>= 1; } return res; }
ll binpow(ll a, ll b, ll m) { a %= m; long long res = 1; while (b > 0) { if (b & 1) res = res * a % m; a = a * a % m; b >>= 1; } return res; } // For a < 2^31

#if 1
auto Start = chrono::high_resolution_clock::now();
void resettimer() { Start = chrono::high_resolution_clock::now(); }
int elapsedmillis() { return chrono::duration_cast<chrono::milliseconds>(chrono::high_resolution_clock::now() - Start).count(); }
random_device rd;
mt19937 rng(rd());
template<typename T, typename U> inline int randint(T lo, U hi) { return uniform_int_distribution<int>((int)lo, (int)hi)(rng); } // [lo,hi]
template<typename T> inline T randel(vector<T>& v) { return v[uniform_int_distribution<int>(int(0), int(v.size()) - int(1))(rng)]; } // [lo,hi]
#endif
const ll mod = 1e9 + 7;
vp2 dirs = { {0,1},{0,-1},{1,0},{-1,0} };

const int hi = int(2e5 + 10);
struct LCA
{
    LCA() {}
    LCA(vvi& edges)
    {
        dfs(0, 0, 0, edges);
    }

    int up[19][hi];
    int depth[hi];
    int tin[hi];
    int tout[hi];
    int timer = 0;
    void dfs(int u, int p, int d, vvi& edges)
    {
        up[0][u] = p;
        repp(d, 1, 19) up[d][u] = up[d-1][up[d - 1][u]];

        depth[u] = d;
        tin[u] = timer++;

        repe(e, edges[u])
        {
            if (e == p) continue;
            dfs(e, u, d + 1, edges);
        }
        tout[u] = timer++;
    }

    bool isancestor(int a, int b)
    {
        return tin[a] <= tin[b] && tout[a] >= tout[b];
    }

    int lca(int a, int b)
    {
        if (isancestor(a, b)) return a;
        if (isancestor(b, a)) return b;

        per(d, 19)
        {
            if (!isancestor(up[d][a], b)) a = up[d][a];
        }

        return up[0][a];
    }

    int dist(int a, int b)
    {
        int c = lca(a, b);
        return depth[a] + depth[b] - 2 * depth[c];
    }
};

struct Centroid
{
    int n;
    vvi edges;
    vb vis;
    vi par;
    vi size;

    Centroid() {}
    Centroid(vvi& edges) : edges(edges), n(edges.size()), vis(n),par(n),size(n)
    {
        init_centroid(0, -1);
    }

    int find_centroid(int u, int p, int n)
    {
        repe(e, edges[u])
        {
            if (e == p) continue;
            if (!vis[e] && size[e] > n / 2) return find_centroid(e, u, n);
        }
        return u;
    }

    int find_size(int u, int p)
    {
        if (vis[u]) return 0;
        size[u] = 1;

        repe(e, edges[u])
        {
            if (e == p) continue;
            size[u] += find_size(e, u);
        }
        return size[u];
    }

    void init_centroid(int u, int p)
    {
        find_size(u, u);

        int c = find_centroid(u, u, size[u]);
        vis[c] = 1;
        par[c] = p;

        repe(e, edges[c])
        {
            if (!vis[e]) init_centroid(e, c);
        }
    }
};

Centroid centroid;
LCA lca;
vi best;
void update(int u)
{
    int v = u;
    do 
    {
        best[v] = min(best[v], lca.dist(v, u));
        v = centroid.par[v];
    } while (v != -1);
}

int query(int u)
{
    int ans = inf;

    int v = u;
    do
    {
        ans = min(ans, best[v] + lca.dist(v, u));
        v = centroid.par[v];
    } while (v!=-1);

    return ans;
}

int32_t main()
{
    fast();
#if 1 && _LOCAL
    ifstream instream("C:\\users\\matis\\Desktop\\comp_prog\\x64\\debug\\in.txt");
    cin.rdbuf(instream.rdbuf());
#endif

    dread2(int, n, d);
    best.resize(n, inf);
    vvi edges(n);
    rep(i,n-1)
    {
        dread(int, p);
        edges[i+1].push_back(p);
        edges[p].push_back(i+1);
    }
    lca = LCA(edges);
    centroid = Centroid(edges);

    priority_queue<p2> pq;
    rep(i, n)
    {
        pq.emplace(lca.depth[i], i);
    }

    int ans = 0;
    while (pq.size())
    {
        int _, u;
        tie(_, u) = pq.top(); pq.pop();
        //cerr << query(u) << " " << u << "\n";
        if (query(u) < d) continue;
        update(u);
        ans++;
    }
    cout << ans;

    quit;
}

Compilation message (stderr)

catinatree.cpp: In constructor 'Centroid::Centroid(vvi&)':
catinatree.cpp:207:9: warning: 'Centroid::edges' will be initialized after [-Wreorder]
  207 |     vvi edges;
      |         ^~~~~
catinatree.cpp:206:9: warning:   'll Centroid::n' [-Wreorder]
  206 |     int n;
      |         ^
catinatree.cpp:213:5: warning:   when initialized here [-Wreorder]
  213 |     Centroid(vvi& edges) : edges(edges), n(edges.size()), vis(n),par(n),size(n)
      |     ^~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49