Submission #1145632

#	Time	Username	Problem	Language	Result	Execution time	Memory
1145632		Issa	Highway Tolls (IOI18_highway)	C++20	51 / 100	65 ms	10008 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;

const int maxn = 1e5 + 100;

int n, m;
vector<pii> g[maxn];
vector<int> s[2];
int t[maxn];
int f[maxn];
ll dist;

int calc(vector<int> s){
    int v = -1;
    for(int l = 0, r = s.size()-1; l <= r;){
        int mid = (l + r) >> 1;
        vector<int> q(m, 0);
        for(int i = 0; i <= mid; i++){
            q[f[s[i]]] = 1;
        } if(ask(q) == dist) l = mid + 1;
        else r = mid - 1, v = s[mid];
    } return v;
}

void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
    n = N; m = U.size();
    dist = ask(vector<int>(m, 0));
    for(int i = 0; i < n - 1; i++){
        int a = U[i], b = V[i];
        g[a].push_back({b, i});
        g[b].push_back({a, i});
    }
    int i;
    for(int l = 0, r = m; l <= r;){
        int mid = (l + r) >> 1;
        vector<int> q(m, 0);
        for(int j = 0; j <= mid; j++){
            q[j] = 1;
        }
        if(ask(q) == dist) l = mid + 1;
        else r = mid - 1, i = mid;
    }
    fill(t, t + n, -1);
    t[V[i]] = 1;
    t[U[i]] = 0;
    queue<int> q;
    q.push(V[i]);
    q.push(U[i]);
    while(q.size()){
        int v = q.front();
        q.pop();
        for(auto [to, i]: g[v]){
            if(t[to] == -1){
                t[to] = t[v];
                s[t[v]].push_back(to);
                f[to] = i;
                q.push(to);
            }
        }
    } for(int c = 0; c < 2; c++){
        reverse(s[c].begin(), s[c].end());
    } int a = calc(s[0]);
    int b = calc(s[1]);
    if(a == -1) a = U[i];
    if(b == -1) b = V[i];
    answer(a, b);
    // cout << a << ' ' << b << endl;
}

• Subtask 1: 5 / 5
• Subtask 2: 7 / 7
• Subtask 3: 6 / 6
• Subtask 4: 33 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31