Submission #724348

#	Time	Username	Problem	Language	Result	Execution time	Memory
724348		PixelCat	Split the Attractions (IOI19_split)	C++14	33 / 100	152 ms	43456 KiB

split

#include "split.h"
#ifdef NYAOWO
#include "grader.cpp"
#endif

#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i <= b; i++)
#define Forr(i, a, b) for(int i = a; i >= b; i--)
#define F first
#define S second
#define eb emplace_back
#define sz(x) ((int)x.size())
#define all(x) x.begin(), x.end()
// #define int LL
using namespace std;
using LL = long long;
using pii = pair<int, int>;

const int MAXN = 200010;

vector<pii> edge;
vector<int> adj[MAXN];
vector<int> tr[MAXN];
int siz[MAXN];
int vis[MAXN];

int nbcc;
vector<int> bcc[MAXN];
int d[MAXN];
int lo[MAXN];

void link_tr(int a, int b) {
    edge.eb(a, b);
    tr[a].eb(b);
    tr[b].eb(a);
}

vector<int> st;
void dfs_ap(int n, int dep) {
    d[n] = lo[n] = dep;
    st.eb(n);
    for(auto &i:adj[n]) {
        if(d[i]) {
            lo[n] = min(lo[n], d[i]);
        } else {
            dfs_ap(i, dep + 1);
            lo[n] = min(lo[n], lo[i]);

            // bcc found
            if(lo[i] >= d[n]) {
                while(st.back() != n) {
                    bcc[nbcc].eb(st.back());
                    st.pop_back();
                }
                bcc[nbcc].eb(n);
                nbcc++;
            }
        }
    }
}

int dfs_siz(int n, int p, int N) {
    siz[n] = (n < N);
    for(auto &i:tr[n]) if(i != p) {
        siz[n] += dfs_siz(i, n, N);
    }
    // cerr << n << " = " << siz[n] << "\n";
    return siz[n];
}

vector<int> comp(int n, int ban, int cnt, int N) {
    memset(vis, 0, sizeof(vis));
    // vis[ban] = 1; vis[n] = 1;
    if(n < N) { // n is ap, ban is bcc
        int bid = ban - N;
        for(auto &i:bcc[bid]) vis[i] = 1;
    } else { // ban is ap, n is bcc
        int bid = n - N;
        for(auto &i:bcc[bid]) if(i != ban) {
            n = i; break;
        }
        vis[ban] = 1; vis[n] = 1;
    }

    queue<int> que;
    que.emplace(n);
    vector<int> res;
    while(!que.empty()) {
        int cur = que.front(); que.pop();
        res.eb(cur);
        cnt--;
        if(cnt == 0) return res;
        
        for(auto &i:adj[cur]) if(!vis[i]) {
            vis[i] = 1;
            que.emplace(i);
        }
    }
    assert(false);
    return res;
}

vector<int32_t> find_split(int32_t n, int32_t a, int32_t b, int32_t c, vector<int32_t> p, vector<int32_t> q) {
    int x, y;
    int ix, iy;
    {
        vector<pii> ord = {{a, 1}, {b, 2}, {c, 3}};
        sort(all(ord));
        x = ord[0].F; ix = ord[0].S;
        y = ord[1].F; iy = ord[1].S;
    }

    int m = sz(p);
    // assert(m == n - 1);
    For(i, 0, m - 1) {
        int s = p[i];
        int t = q[i];
        adj[s].eb(t);
        adj[t].eb(s);
    }

    nbcc = 0;
    dfs_ap(0, 1);
    For(i, 0, nbcc - 1) {
        // cerr << sz(bcc[i]) << ":";
        for(auto &j:bcc[i]) {
            // cerr << " " << j;
            link_tr(n + i, j);
        }
        // cerr << "\n";
    }
    // return vector<int>(n, 0);

    dfs_siz(0, -1, n);
    for(auto &e:edge) {
        int s = e.F;
        int t = e.S;
        if(siz[s] < siz[t]) swap(s, t);
        // s is parent
        int s1 = siz[t];
        int s2 = n - s1;
        if(s1 > s2) {
            swap(s1, s2);
            swap(s, t);
        }
        // size of t's side is smaller (s1)
        if(s1 >= x && s2 >= y) {
            // cerr << "! " << s << " " << t << "\n";
            vector<int> v1 = comp(t, s, x, n);
            vector<int> v2 = comp(s, t, y, n);

            vector<int> res(n, 6 - ix - iy);
            for(auto &i:v1) res[i] = ix;
            for(auto &i:v2) res[i] = iy;
            return res;
        }
    }
    return vector<int>(n, 0);
}

• Subtask 1: 0 / 7
• Subtask 2: 11 / 11
• Subtask 3: 22 / 22
• Subtask 4: 0 / 24
• Subtask 5: 0 / 36