Submission #1352358

#TimeUsernameProblemLanguageResultExecution timeMemory
1352358yyc000123Fun Tour (APIO20_fun)C++20
100 / 100
120 ms21376 KiB
#include<bits/stdc++.h>
using namespace std ;
#define F first
#define S second
const int N = 1e5+5 ;
const int Q = 4e5+5 ;
int sub[N] , deep[N] ;
vector<int> ans , son ;
vector<vector<int>> subtr ;

int hoursRequired(int x , int y) ;
int attractionsBehind(int x , int y) ;

vector<int> createFunTour(int n , int q){
    if(n==2) return {0,1} ;
    int pos = -1 ;
    for(int i=0 ; i<n ; i++){
        sub[i]=attractionsBehind(0,i) ;
        if(sub[i]>=(n+1)/2 && (pos==-1 || sub[i]<sub[pos])) pos = i ; 
    }
    for(int i=0 ; i<n ; i++){
        deep[i]=hoursRequired(pos,i) ;
        if(deep[i]==1) son.push_back(i) ;
    }
    subtr.resize(son.size()) ;
    for(int i=0 ; i<n ; i++){
        if(i==pos) continue ;
        for(int j=0 ; j<3 ; j++){
            if(j==2) subtr[j].push_back(i) ;
            else if(deep[i]-deep[son[j]]==hoursRequired(i,son[j])) subtr[j].push_back(i) ;
            else continue ;
            break ;
        }
    }

    auto cmp = [&](const int &x, const int &y) -> bool {
        return deep[x] < deep[y];
    };

    int sum = 0;
    std::pair<int, int> max(0, -1);

    for (int i = 0; i < 3; i++) {
        sum += subtr[i].size();
        max = std::max(max, std::make_pair((int)subtr[i].size(), i));
    }

    if (std::abs((sum - max.first) - max.first) <= 1) {
        std::vector<int> idx;

        for (int i = 0; i < 3; i++)
            if (i != max.second)
                idx.push_back(i);

        subtr[idx[0]].insert(subtr[idx[0]].end(), subtr[idx[1]].begin(), subtr[idx[1]].end());
        subtr.erase(subtr.begin() + idx[1]);
        son.erase(son.begin() + idx[1]);
    }

    for (auto &tr : subtr)
        std::sort(tr.begin(), tr.end(), cmp);

    int last = -1, lastdis = 1e9;

    if ((int)son.size() == 3) {
        for (int i = 0; i < 3; i++)
            if (last == -1 || deep[subtr[last].back()] < deep[subtr[i].back()])
                last = i;

        ans.push_back(subtr[last].back());
        subtr[last].pop_back();

        while (true) {
            int nxt = -1;

            for (int i = 0; i < 3; i++)
                if (i != last && (nxt == -1 || deep[subtr[nxt].back()] < deep[subtr[i].back()]))
                    nxt = i;

            ans.push_back(subtr[nxt].back());
            subtr[nxt].pop_back();

            int sum = 0;
            std::pair<int, int> max(0, -1);

            for (int i = 0; i < 3; i++) {
                sum += subtr[i].size();
                max = std::max(max, std::make_pair((int)subtr[i].size(), i));
            }

            if (std::abs((sum - max.first) - max.first) <= 1) {
                std::vector<int> idx;

                for (int i = 0; i < 3; i++)
                    if (i != max.second)
                        idx.push_back(i);

                if (nxt == idx[0] && deep[ans.back()] < deep[subtr[idx[1]].back()])
                    nxt = idx[1], ans.push_back(subtr[nxt].back()), subtr[nxt].pop_back();
                else if (nxt == idx[1] && deep[ans.back()] < deep[subtr[idx[0]].back()])
                    nxt = idx[0], ans.push_back(subtr[nxt].back()), subtr[nxt].pop_back();

                if (nxt == idx[1])
                    nxt = idx[0];

                if (nxt >= idx[1])
                    --nxt;

                subtr[idx[0]].insert(subtr[idx[0]].end(), subtr[idx[1]].begin(), subtr[idx[1]].end());
                std::sort(subtr[idx[0]].begin(), subtr[idx[0]].end(), cmp);
                subtr.erase(subtr.begin() + idx[1]);
                last = nxt;
                break;
            }

            last = nxt;
        }
    } else {
        last = (deep[subtr[0].back()] > deep[subtr[1].back()]) ? 0 : 1;
        ans.push_back(subtr[last].back());
        subtr[last].pop_back();
    }

    while (true) {
        int nxt = last ^ 1;
        ans.push_back(subtr[nxt].back());
        subtr[nxt].pop_back();

        if (subtr[last].empty() && (int)subtr[nxt].size() == 1) {
            ans.push_back(subtr[nxt].back());
            ans.push_back(pos);
            return ans;
        }

        if (ans.size() == n - 1) {
            ans.push_back(pos);
            return ans;
        }

        last ^= 1;
    }
}

/*
int hoursRequired(int x , int y){
    cout << "h " << x << ' ' << y << '\n' ;
    int k ; cin >> k ; return k ;
}
int attractionsBehind(int x , int y){
    cout << "a " << x << ' ' << y << '\n' ;
    int k ; cin >> k ; return k ;
}
int main(){
    vector<int> v = createFunTour(7,Q-5) ; for(int i:v) cout << i << ' ' ; cout << '\n' ;
    return 0 ;
}
*/
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