Submission #982577

#	Time	Username	Problem	Language	Result	Execution time	Memory
982577		phoenix	Fun Tour (APIO20_fun)	C++17	31 / 100	87 ms	15552 KiB

fun

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

#define get_dist hoursRequired
#define get_size attractionsBehind

#ifdef LOCAL 
#define cerr cout
#else 
#define cerr if (false) cout
#endif


using namespace std;

vector<int> createFunTour(int n, int q) {
    vector<int> res;
    int C;
    vector<pair<int, int>> d[3];
    vector<int> dist(n);

    /*Step 1: Find Centroid */ {
        // a) pick a random vertex
        int v = 0;
        // b) for all i, find i's subtree's size if tree is rooted by v
        vector<int> sz(n);
        for (int i = 0; i < n; i++)
            sz[i] = get_size(v, i);
        // c) centroid is i s.t, 2 * sz[i] > n and sz[i] - min
        C = -1;
        for (int i = 0; i < n; i++)
            if (2 * sz[i] > n) 
                if (C == -1 || sz[i] < sz[C]) 
                    C = i;
    }       

    /*Step 2: Find distance from C to any other vertices*/ {
        for (int i = 0; i < n; i++)
            dist[i] = get_dist(C, i);
    }

    /*Step 3: Divide all vertices to subrees of C*/ {
        vector<int> c;
        for (int i = 0; i < n; i++) 
            if (dist[i] == 1)
                c.push_back(i);
        
        for (int i = 0; i < n; i++) {
            if (i == C) continue;
            int j = 0;
            while (j < (int)c.size() - 1) {
                if (get_dist(i, c[j]) < dist[i]) break;
                j++;
            }
            d[j].push_back({dist[i], i});
        }
    }

    for (int i = 0; i < 3; i++) {
        sort(d[i].rbegin(), d[i].rend());
    }

    /*Step 4: Solve problem :)*/ {
        res.push_back(C);

        int lst = -1;
        while ((int)res.size() < n) {
            cerr << "oper: " << (int)res.size() << '\n';
            for (int i = 0; i < 3; i++) {
                cerr << "{";
                for (auto [x, y] : d[i]) cerr << '(' << x << ' ' << y << ") ";
                cerr << "}\n";
            }
            cerr << '\n';
            int s = 0;
            for (int i = 0; i < 3; i++) 
                s += (int)d[i].size();
            
            int nxt = -1;
            for (int i = 0; i < 3; i++) {
                if (d[i].empty() || i == lst) 
                    continue;
                if ((int)d[i].size() * 2 > s) {
                    nxt = i;
                    break;
                } 
                if (nxt == -1 || d[i].back().first < d[nxt].back().first)
                    nxt = i;
            }
            assert(nxt != -1);
            res.push_back(d[nxt].back().second);
            d[nxt].pop_back();
            lst = nxt;
        }
    }
    for (int c : res)   
        cerr << c << ' ';
    cerr << '\n';
    reverse(res.begin(), res.end());

    return res;
}

• Subtask 1: 10 / 10
• Subtask 2: 0 / 16
• Subtask 3: 21 / 21
• Subtask 4: 0 / 19
• Subtask 5: 0 / 34