Submission #1259026

#	Time	Username	Problem	Language	Result	Execution time	Memory
1259026		biank	Sphinx's Riddle (IOI24_sphinx)	C++20	50 / 100	522 ms	1232 KiB

sphinx

#include "sphinx.h"
#include <bits/stdc++.h>
 
#define forsn(i, s, n) for (int i = int(s); i < int(n); i++)
#define forn(i, n) forsn(i, 0, n)
#define dforsn(i, s, n) for (int i = int(n) - 1; i >= int(s); i--)
#define dforn(i, n) dforsn(i, 0, n)
 
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
 
#define pb push_back
#define eb emplace_back
 
#define fst first
#define snd second
 
using namespace std;
 
using vi = vector<int>;
using ii = pair<int, int>;
using ll = long long;

struct DSU {
    vi p;
    DSU(int n) : p(n, -1) {}
    int find(int x) {
        if (p[x] < 0) return x;
        return p[x] = find(p[x]);
    }
    bool unite(int x, int y) {
        x = find(x), y = find(y);
        if (x == y) return false;
        if (p[x] > p[y]) swap(x, y);
        return p[x] += p[y], p[y] = x, true;
    }
};

vector<vi> eraseEmpty(const vector<vi> &a) {
    vector<vi> b;
    for (auto v : a) if (!v.empty()) b.pb(v);
    return b;
}

vi find_colours(int N, vi X, vi Y) {
    vector<vi> adj(N);
    forn(i, sz(X)) {
        adj[X[i]].pb(Y[i]);
        adj[Y[i]].pb(X[i]);
    }
    DSU dsu(N);
    forsn(i, 1, N) {
        vi E(N);
        forn(j, N) E[j] = j <= i ? -1 : N;
        auto expected = [&]() {
            queue<int> q;
            vector<bool> vis(N, false);
            int cmps = 0;
            forn(j, N) if (!vis[j]) {
                q.push(j), cmps++, vis[j] = true;
                while (!q.empty()) {
                    int u = q.front();
                    q.pop();
                    for (int v : adj[u]) {
                        if (vis[v]) continue;
                        if (E[u] != E[v]) continue;
                        if (E[u] == N || dsu.find(u) == dsu.find(v)) {
                            q.push(v), vis[v] = true;
                        }
                    }
                }
            }
            return cmps;
        };
        while (true) {
            vector<vi> comps(i);
            for (int j : adj[i]) if (j < i) {
                int p = dsu.find(j);
                assert(p < i);
                comps[p].pb(j);
            }
            comps = eraseEmpty(comps);
            int lo = 0, hi = sz(comps) + 1;        
            while (hi - lo > 1) {
                int mid = (lo + hi) / 2;
            E = vi(N, N);
            E[i] = -1;
            forn(idx, mid) for (int j : comps[idx]) E[j] = -1;
                if (perform_experiment(E) == expected()) {
                    lo = mid;
                } else {
                    hi = mid;
                }
            }
            if (lo < sz(comps)) dsu.unite(comps[lo].back(), i);
            else break;
        }
    }
    vi C(N);
    forn(i, N) C[i] = dsu.find(i);
    return C;
}

• Subtask 0: 0 / 0
• Subtask 1: 1.5 / 3
• Subtask 2: 3.5 / 7
• Subtask 3: 16.5 / 33
• Subtask 4: 10.5 / 21
• Subtask 5: 18 / 36