Submission #1249202

#	Time	Username	Problem	Language	Result	Execution time	Memory
1249202		qwerasdfzxcl	Sphinx's Riddle (IOI24_sphinx)	C++20	50 / 100	259 ms	1156 KiB

sphinx

#include "sphinx.h"
#include <bits/stdc++.h>

using namespace std;
using ll = long long;

struct DSU{
    int path[2020];

    void init(int n){
        for (int i=0;i<n;i++) path[i] = i;
    }

    int find(int s){
        if (s==path[s]) return s;
        return path[s] = find(path[s]);
    }

    int merge(int x, int y){
        x = find(x), y = find(y);
        if (x==y) return 0;
        path[x] = y;
        return 1;
    }
}dsu, dsu2;

int N;
vector<int> X, Y;

int query(vector<int> Q){
    int ret = N;
    dsu2.init(N);

    for (int i=0;i<(int)X.size();i++){
        if (Q[X[i]] >= 0 && Q[X[i]] == Q[Y[i]]) ret -= dsu2.merge(X[i], Y[i]);
        if (Q[X[i]] == -1 && Q[Y[i]] == -1 && dsu.find(X[i]) == dsu.find(Y[i])) ret -= dsu2.merge(X[i], Y[i]);
    }

    ret -= perform_experiment(Q);
    assert(ret >= 0);
    
    return ret;
}

std::vector<int> find_colours(int N, std::vector<int> X, std::vector<int> Y) {
    ::N = N, ::X = X, ::Y = Y;
    dsu.init(N);

    for (int i=0;i<N;i++){
        vector<int> Q(N, N);
        for (int j=0;j<=i;j++) Q[j] = -1;

        int t = query(Q);
        
        while(t--){
            vector<int> adj;
            
            for (int j=0;j<(int)X.size();j++){
                int x = dsu.find(X[j]), y = dsu.find(Y[j]);
                if (x == y) continue;
                if (x == dsu.find(i) && y < i) adj.push_back(y);
                if (x < i && y == dsu.find(i)) adj.push_back(x);
            }

            sort(adj.begin(), adj.end());
            adj.erase(unique(adj.begin(), adj.end()), adj.end());

            int l = 0, r = (int)adj.size() - 1, v = (int)adj.size();
            while(l<=r){
                int mid = (l+r)>>1;
                vector<int> Q(N, N);

                for (int j=0;j<N;j++){
                    if (dsu.find(j) == dsu.find(i)) Q[j] = -1;
                    if (find(adj.begin(), adj.end(), dsu.find(j)) - adj.begin() <= mid) Q[j] = -1;
                }

                if (query(Q) > 0) r = mid-1, v = mid;
                else l = mid+1;
            }

            if (v == (int)adj.size()){
                if (query(Q) == 0) return {};
            }
            assert(v < (int)adj.size());
            dsu.merge(i, adj[v]);
        }
    }

    vector<int> ret(N);
    for (int i=0;i<N;i++) ret[i] = dsu.find(i);
    
    return ret;
}

• 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