Submission #1194930

#	Time	Username	Problem	Language	Result	Execution time	Memory
1194930		steveonalex	Towns (IOI15_towns)	C++20	100 / 100	10 ms	328 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(abs(a), abs(b));}
ll lcm(ll a, ll b){return abs(a) / gcd(a, b) * abs(b);}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ull mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
// mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

namespace Sub2{
    mt19937_64 rng(1);
    int solve(int n){

        int dih = 0;
        int u = 0;
        vector<int> dis2(n);
        for(int i = 1; i < n; ++i) {
            dis2[i] = getDistance(0, i);
            if (maximize(dih, dis2[i])) 
                u = i;
        }
        vector<int> dis1(n);
        for(int i = 0; i < n; ++i) if (i != u && i != 0) {
            dis1[i] = getDistance(i, u);
            maximize(dih, dis1[i]);
        }
        dis1[0] = dis2[u];

        vector<int> left_dis(n), stick_out(n);
        int ans = 1e9 + 69;
        int ma = 0;
        for(int i = 0; i < n; ++i) if (i != u && i != 0){
            int x = dis1[i], y = dis2[i];
            int cur = (x - y + dis1[0]) / 2;
            left_dis[i] = cur;
            maximize(ma, left_dis[i]);
        }
        left_dis[0] = ma;
        for(int i = 0; i < n; ++i) {
            stick_out[i] = dis1[i] - left_dis[i];
            int cur = left_dis[i];
            maximize(cur, dih - left_dis[i]);
            minimize(ans, cur);
        }

        vector<int> possible = left_dis; remove_dup(possible);
        for(int i: possible){
            if (max(i, dih - i) != ans) continue;
            array<int, 3> cnt; fill(ALL(cnt), 0);
            vector<int> S;
            for(int j = 0; j < n; ++j) {
                if (left_dis[j] < i) cnt[0]++;
                else if (left_dis[j] == i) {
                    cnt[1]++;
                    S.push_back(j);
                }
                else cnt[2]++;
            }
            if (*max_element(ALL(cnt)) <= n / 2) return ans;
            if (max(cnt[0], cnt[2]) <= n / 2){
                vector<int> st1, st2;
                for(int j: S){
                    if (st1.empty()) st1.push_back(j);
                    else{
                        if (getDistance(st1.back(), j) != stick_out[st1.back()] + stick_out[j]) st2.push_back(j); // same set
                        else{
                            st1.push_back(j);
                            if (st2.size()) {
                                st1.push_back(st2.back());
                                st2.pop_back();
                            }
                        }
                    }
                }

                int t = st1.back(); 
                bool check = true;
                while(st1.size()){
                    if (getDistance(st1.back(), t) != stick_out[st1.back()] + stick_out[t]){ // same set
                        if (st1.size() < 2) break;
                        st1.pop_back(); st1.pop_back();
                    }   
                    else{
                        if (st2.empty()) {
                            check = false;
                            break;
                        }
                        st1.pop_back(); st2.pop_back();
                    }
                }
                int wow = n / 2 + 1;
                wow = 2 * wow - S.size();
                if (st1.size() + st2.size() < wow) check = false;

                if (!check) return ans;
            }
        }

        return -ans;

    }
}

int hubDistance(int n, int subtask){
    return Sub2::solve(n);
}

// int main(void){
//     ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);

//     clock_t start = clock();

//     cerr << "Time elapsed: " << clock() - start << " ms!\n";

//     return 0;
// }

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 10 / 10
• Subtask 5: 13 / 13
• Subtask 6: 39 / 39