Submission #497127

#	Time	Username	Problem	Language	Result	Execution time	Memory
497127		dxz05	통행료 (IOI18_highway)	C++14	0 / 100	215 ms	262148 KiB

highway

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

using namespace std;

typedef long long ll;

#define all(x) (x).begin(), (x).end()

const int MAXN = 1e5 + 3e2;

vector<int> edges;
vector<pair<int, int>> g[MAXN];

void dfs(int v, int p){
    for (auto e : g[v]){
        int u = e.first, i = e.second;
        if (u != p){
            edges.push_back(i);
            dfs(u, v);
        }
    }
}

vector<pair<int, int>> vec;
int dep;
void dfs2(int v, int p, int d){
    for (auto e : g[v]){
        int u = e.first, i = e.second;
        if (u != p){
            if (d + 1 == dep) vec.emplace_back(i, u);
            dfs2(u, v, d + 1);
        }
    }
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
    int M = U.size();

    for (int i = 0; i < M; i++){
        g[U[i]].emplace_back(V[i], i);
        g[V[i]].emplace_back(U[i], i);
    }

    dfs(0, 0);

    vector<int> w(M, 0);

    ll onlyA = ask(w);

    int ind = 0;

    int l = 0, r = M - 1;
    while (l <= r){
        int mid = (l + r) >> 1;

        fill(all(w), 0);
        for (int i = 0; i <= mid; i++) w[edges[i]] = 1;

        int res = ask(w);
        if (res != onlyA){
            ind = mid;
            r = mid - 1;
        } else l = mid + 1;

    }

    for (int i = 0; i < g[U[ind]].size(); i++){
        if (g[U[ind]][i].first == V[ind]) g[U[ind]].erase(g[U[ind]].begin() + i);
    }
    for (int i = 0; i < g[V[ind]].size(); i++){
        if (g[V[ind]][i].first == U[ind]) g[V[ind]].erase(g[V[ind]].begin() + i);
    }

    if (g[U[ind]].empty() && g[V[ind]].empty()){
        answer(U[ind], V[ind]);
        return;
    }

    if (!g[U[ind]].empty() && g[U[ind]][0].second > ind) swap(U[ind], V[ind]);
    if (!g[V[ind]].empty() && g[V[ind]][0].second < ind) swap(U[ind], V[ind]);

    int S = 0, T = 0;

    fill(all(w), 0);
    for (int i = 0; i < ind; i++){
        w[edges[i]] = 1;
    }

    ll res = ask(w);

    dep = (res - onlyA) / (B - A);
    if (dep != 0) {
        dfs2(U[ind], U[ind], 0);

        l = 0, r = vec.size() - 1;
        while (l <= r){
            int mid = (l + r) >> 1;
            fill(all(w), 0);
            for (int i = 0; i <= mid; i++) w[vec[i].first] = 1;

            res = ask(w);
            if (res != onlyA){
                S = vec[mid].second;
                r = mid - 1;
            } else l = mid + 1;
        }
    } else S = U[ind];

    fill(all(w), 0);
    for (int i = ind + 1; i < M; i++){
        w[edges[i]] = 1;
    }

    res = ask(w);

    dep = (res - onlyA) / (B - A);
    if (dep != 0) {
        vec.clear();
        dfs2(V[ind], V[ind], 0);

        l = 0, r = vec.size() - 1;
        while (l <= r){
            int mid = (l + r) >> 1;
            fill(all(w), 0);
            for (int i = 0; i <= mid; i++) w[vec[i].first] = 1;

            res = ask(w);
            if (res != onlyA){
                T = vec[mid].second;
                r = mid - 1;
            } else l = mid + 1;
        }
    } else T = V[ind];

    answer(S, T);
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:68:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |     for (int i = 0; i < g[U[ind]].size(); i++){
      |                     ~~^~~~~~~~~~~~~~~~~~
highway.cpp:71:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   71 |     for (int i = 0; i < g[V[ind]].size(); i++){
      |                     ~~^~~~~~~~~~~~~~~~~~

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