Submission #207296

#	Time	Username	Problem	Language	Result	Execution time	Memory
207296		AQT	Towns (IOI15_towns)	C++14	35 / 100	27 ms	504 KiB

towns

#include <towns.h>
#include <bits/stdc++.h>

using namespace std;

int dist[2][200];
int par[200], sz[200];
bool midset[200];
/*
int getDistance(int i, int j){
    cout << "? " << i << " " << j << endl;
    int k;
    cin >> k;
    return k;
}
*/

int hubDistance(int N, int sub){
    int d1 = 0, d2 = 0;
    for(int i = 1; i<N; i++){
        dist[0][i] = getDistance(0, i);
        if(dist[0][i] > dist[0][d1]){
            d1 = i;
        }
    }
    for(int i = 0; i<N; i++){
        dist[1][i] = getDistance(d1, i);
        if(dist[1][i] > dist[1][d2]){
            d2 = i;
        }
    }
    int dia = dist[1][d2];
    //cout << "diameter endpoints: " << d1 << " " << d2 << endl;
    int ans = dia;
    for(int i = 0; i<N; i++){
        int k = (dist[0][d1] + dist[1][i] - dist[0][i])/2;
        //cout << "which set?: " << i << " " << k << endl;
        if(abs(ans-dia/2) > abs(k-dia/2)){
            ans = k;
        }
        midset[i] = 0;
    }
    ans = max(ans, dia-ans);
    int lft = 0, rht = 0;
    for(int i = 0; i<N; i++){
        int k = (dist[0][d1] + dist[1][i] - dist[0][i])/2;
        //cout << "which set again?: " << i << " " << k << endl;
        //cout << dist[0][d1] << " " << dist[1][i] << " " << dist[0][i] << endl;
        if(dia-k > ans){
            //cout << "lft: " << i << endl;
            midset[i] = 1;
            lft++;
        }
        else if(k > ans){
            //cout << "rht: " << i << endl;
            midset[i] = 1;
            rht++;
        }
    }
    if(max(lft, rht) > N/2){
        ans = -ans;
        return ans;
    }
    vector<int> v, w;
    for(int i =0 ; i<N; i++){
        if(midset[i]){
            par[i] = -1;
            continue;
        }
        par[i] = i;
        v.push_back(i);
        sz[i] = 1;
    }
    int g = -1;
    while(v.size()){
        //cout << "next iteration: " << k << endl;
        while(v.size() >= 2){
            int n = v.back();
            v.pop_back();
            int m = v.back();
            v.pop_back();
            if(dist[1][n] + dist[1][m] - getDistance(n, m) > 2*ans){
                par[n] = -1;
                sz[m] += sz[n];
                w.push_back(m);
            }
        }
        if(v.size() == 1 && w.empty()){
            g = v[0];
            break;
        }
        swap(v, w);
        w.clear();
    }
    if(g != -1){
        int cnt = 0;
        for(int i = 0; i<N; i++){
            if(par[i] == i && !midset[i]){
                if(dist[1][i] + dist[1][g] - getDistance(i, g) > 2*ans){
                    cnt += sz[i];
                    //cout << "sz: " << i << " " << sz[i] << endl;
                }
            }
        }
        //cout << cnt << endl;
        if(cnt > N/2){
            ans = -ans;
        }
    }
    else{
        ans = -ans;
    }
    return ans;
}
/*
int main(){
    cout << hubDistance(11, 0) << endl;
}
*/

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:18:28: warning: unused parameter 'sub' [-Wunused-parameter]
 int hubDistance(int N, int sub){
                            ^~~

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 10 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39