Submission #309358

#	Time	Username	Problem	Language	Result	Execution time	Memory
309358		xt0r3	Stations (IOI20_stations)	C++14	100 / 100	1249 ms	1280 KiB

stations

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

int timer;
vector<bool> f;
vector<int> l, d;
vector<vector<int> > g;

void dfs(int id, bool flag = 1){
    d[id] = timer++;
    f[id] = flag;
    for(int v : g[id]) if(d[v] == -1) dfs(v, !flag);
    l[id] = timer++;
}

vector<int> label(int n, int k, vector<int> u, vector<int> v){
    f.resize(n);
    l.assign(n, -1);
    d.assign(n, -1);
    g.assign(n, {});
    for(int i = 0; i < n - 1; i++){
        g[u[i]].push_back(v[i]);
        g[v[i]].push_back(u[i]);
    }
    timer = 0;
    dfs(0);
    vector<int> ret(n);
    for(int i = 0; i < n; i++){
        ret[i] = (f[i] ? d[i] / 2 : l[i] / 2);
    }
    return ret;
}

int find_next_station(int s, int t, vector<int> c){
    if(s < c[0]){
        //c has leaving times
        if(t < s || t > c.back()) return c.back();
        return c[(int)(lower_bound(c.begin(), c.end(), t) - c.begin())];
    }
    else{
        //c has discovery times
        if(t < c.front() || t > s) return c.front();
        return c[(int)(upper_bound(c.begin(), c.end(), t) - c.begin()) - 1];
    }
}
/*
void test(vector<int> ll, vector<int> u, vector<int> v, int id, int t){
    vector<int> c;
    int n = v.size() + 1;
    for(int i = 0; i < n - 1; i++){
        if(u[i] == id) c.push_back(ll[v[i]]);
        if(v[i] == id) c.push_back(ll[u[i]]);
    }
    int got = find_next_station(ll[id], ll[t], c);
    sort(c.begin(), c.end());
    cout << "got: " << got << endl;
    cout << (int)(find(ll.begin(), ll.end(), got) - ll.begin()) << endl;
}

int main(){
    vector<int> v = {0, 0, 0, 1, 1, 4}, u = {1, 4, 6, 2, 3, 5};
    vector<int> labels = label(7, 10, u, v);
    test(labels, u, v, 0, 5);
}
*/

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 16 / 16
• Subtask 4: 10 / 10
• Subtask 5: 61 / 61