Submission #1130047

#	Time	Username	Problem	Language	Result	Execution time	Memory
1130047		math_rabbit_1028	Sphinx's Riddle (IOI24_sphinx)	C++20	36 / 100	51 ms	444 KiB

sphinx

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

vector<int> adj[303];
vector<int> ch;
void dfs(int v) {
    ch[v] = 1;
    for (int u : adj[v]) {
        if (ch[u]) continue;
        dfs(u);
    }
}
int other(int N, int v, int u) {
    int ret = 0;
    ch = vector<int>(N, 0);
    ch[v] = ch[u] = 1;
    for (int i = 0; i < N; i++) {
        if (ch[i]) continue;
        dfs(i);
        ret++;
    }
    return ret;
}

int trivial(vector<int> E) {
    int ret = 1;
    for (int i = 1; i < E.size(); i++) if (E[i] != E[i-1]) ret++;
    return ret;
}

vector<int> vec;
void solve(int s, int e, int x, int N, int r, int c) {
    if (s == e) {
        vec.push_back(3*s+r);
        return;
    }

    int m = (s+e)/2;
    vector<int> E(N, N);
    for (int i = s; i <= m; i++) {
        E[3*i+r] = -1;
        E[3*i+r+1] = c;
    }
    int y = trivial(E) - perform_experiment(E);
    if (y > 0) solve(s, m, y, N, r, c);
    if (x-y > 0) solve(m+1, e, x-y, N, r, c);
}

vector<int> find_colours(int N, vector<int> X, vector<int> Y) {
    for (int i = 0; i < X.size(); i++) {
        adj[X[i]].push_back(Y[i]);
        adj[Y[i]].push_back(X[i]);
    }

    vector<int> C(N, 0);

    vector<int> color(N, 0);
    for (int i = 0; i < N; i++) color[i] = i;

    if (N <= 2) {
        for (int i = 0; i < N; i++) {
            vector<int> E(N, N);
            E[i] = -1;
            random_shuffle(color.begin(), color.end());
            for (int j = 0; j < N; j++) {
                E[adj[i][0]] = color[j];
                int x = perform_experiment(E);
                if (x - other(N, i, adj[i][0]) == 1) {
                    C[i] = color[j];
                    break;
                }
            }
        }
    }
    else {
        for (int r = 0; r < 3; r++) {
            for (int j = 0; j < N; j++) {
                vector<int> E(N, N);
                int cnt = 0;
                for (int i = 0; i < N-1; i++) {
                    if (i % 3 == r) {
                        E[i] = -1;
                        cnt++;
                    }
                }
                for (int i = 1; i < N; i++) {
                    if ((i - 1) % 3 == r) E[i] = color[j];
                }
                int x = trivial(E) - perform_experiment(E);
                if (x > 0) solve(0, cnt-1, x, N, r, color[j]);
                for (auto i : vec) C[i] = color[j];
                vec.clear();
            }
        }

        vector<int> E(N, N);
        E[N-1] = -1;
        random_shuffle(color.begin(), color.end());
        for (int j = 0; j < N; j++) {
            E[N-2] = color[j];
            int x = perform_experiment(E);
            if (x == 2) {
                C[N-1] = color[j];
                break;
            }
        }
    }
    
    return C;
}

• Subtask 0: 0 / 0
• Subtask 1: 3 / 3
• Subtask 2: 0 / 7
• Subtask 3: 33 / 33
• Subtask 4: 0 / 21
• Subtask 5: 0 / 36