Submission #1216609

#	Time	Username	Problem	Language	Result	Execution time	Memory
1216609		the_coding_pooh	Highway Tolls (IOI18_highway)	C++20	18 / 100	1504 ms	327680 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
#define uwu return

using namespace std;

#define fs first
#define sc second

int M;

const int SIZE = 9e4 + 4;

vector <int> graph[SIZE];

long long original_dist;

map<pair<int, int>, int> edge_id;

bool query_edges(vector <pair<int, int>> edges){
    vector<int> w(M);
    for (int i = 0; i < M; ++i) {
        w[i] = 0;
    }
    for(auto i:edges){
        if(!edge_id.count(i))
            continue;
        w[edge_id[i]] = 1;
    }
    return ask(w) != original_dist;
}

map <int, int> parent, order;

int cnt;

void get_dfs_order(int nd, int pa){
    parent[nd] = pa;
    cnt++;
    order[cnt] = nd;
    for(auto i:graph[nd]){
        if(i != pa){
            get_dfs_order(i, nd);
        }
    }
    return;
}

int find_rooted_tree_stuff(int nd, int pa){
    parent.clear(), order.clear();
    cnt = 0;
    get_dfs_order(nd, pa);
    int ret = nd;
    for (int L = 1, R = cnt, M; L != R;){
        M = (L + R + 1) / 2;
        vector <pair<int, int>> block;
        for (int i = M; i <= cnt; i++){
            block.push_back({order[i], parent[order[i]]});
        }
        if(query_edges(block)){
            L = M;
        }
        else{
            R = M - 1;
        }
        ret = order[L];
    }
    return ret;
}

pair <int, int> find_split_edge(int M, vector <int> &U, vector <int> &V){
    int ret = 0;
    for (int l = 0, r = M - 1, m; l != r;){
        m = (l + r + 1) / 2;
        vector <pair<int, int>> block;
        for (int i = m; i < M; i++){
            block.push_back({U[i], V[i]});
        }
        if(query_edges(block)){
            l = m;
        }
        else{
            r = m - 1;
        }
        ret = l;
    }
    return {U[ret], V[ret]};
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B){
    M = U.size();
    vector<int> w(M);
    for (int i = 0; i < M; ++i) {
        w[i] = 0;
    }
    original_dist = ask(w);
    for (int i = 0; i < M; i++){
        edge_id[{U[i], V[i]}] = i;
        edge_id[{V[i], U[i]}] = i;
        graph[U[i]].push_back(V[i]);
        graph[V[i]].push_back(U[i]);
    }
    pair<int, int> split = find_split_edge(M, U, V);
    int s = find_rooted_tree_stuff(split.fs, split.sc), t = find_rooted_tree_stuff(split.sc, split.fs);
    answer(s, t);
    uwu;
}

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