Submission #255329

#	Time	Username	Problem	Language	Result	Execution time	Memory
255329		Erkhemkhuu	Highway Tolls (IOI18_highway)	C++17	0 / 100	41 ms	19196 KiB

highway

#include <bits/stdc++.h>
#include <highway.h>
using namespace std;
#define ll long long
#define pb push_back
#define mp make_pair
#define F first
#define S second
const int N = 150005;
pair <int, int> par[N];
vector < pair <int, int> > adj[N];
int flat[N], timer;
void dfs(int v, int p) {
    flat[timer++] = v;
    for(auto &u: adj[v]) {
        if(u.F == p) continue;
        par[u.F] = {v, u.S};
        dfs(u.F, v);
    }
    return;
}
void find_pair(int n, vector <int> u, vector <int> v, int a, int b) {
    int i, m, l, r, mid, s, t;
    vector <int> w(n - 1);
    ll max_cost;
    m = u.size();
    for(i = 0; i < m; i++) {
        adj[u[i]].pb({v[i], i});
        adj[v[i]].pb({u[i], i});
    }
    dfs(0, -1);
    w.resize(m, 1);
    max_cost = ask(w);
    w.resize(m, 0);
    l = 1; r = n - 1;
    while(l + 1 < r) {
        mid = (l + r) / 2;
        for(i = l; i <= mid; i++)
            w[par[flat[i]].S] = 1;
        if(ask(w) < max_cost) l = mid;
        else {
            r = mid;
            for(i = l; i <= mid; i++)
                w[par[flat[i]].S] = 0;
        }
    }
    s = flat[l + 1];
    w.resize(m, 0);
    timer = 0;
    memset(flat, 0, sizeof(flat));
    memset(par, 0, sizeof(par));
    dfs(s, -1);
    l = 1; r = n - 1;
    while(l + 1 < r) {
        mid = (l + r) / 2;
        for(i = l; i <= mid; i++)
            w[par[flat[i]].S] = 1;
        if(ask(w) < max_cost) l = mid;
        else {
            r = mid;
            for(i = l; i <= mid; i++)
                w[par[flat[i]].S] = 0;
        }
    }
    t = flat[l + 1];
    assert(s >= 0 && s < n && t >= 0 && t < n);
    answer(s, t);
    return;
}

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