Submission #255339

#	Time	Username	Problem	Language	Result	Execution time	Memory
255339		Erkhemkhuu	Highway Tolls (IOI18_highway)	C++17	5 / 100	273 ms	19192 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 <int> w;
vector < 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 run(int l, int r, int type) {
    for(int i = l; i <= r; i++)
        w[par[flat[i]].S] = type;
    return;
}
int go(int l, int r, int max_cost) {
    while(l + 1 < r) {
        int mid = (l + r) / 2;
        run(l, mid, 1);
        if(ask(w) < max_cost) l = mid;
        else {
            r = mid;
            run(l, mid, 0);
        }
    }
    return l + 1;
}
void find_pair(int n, vector <int> u, vector <int> v, int a, int b) {
    int i, m, l, r, mid, s, t;
    ll max_cost;
    m = u.size();
    w.resize(m);
    for(i = 0; i < m; i++) {
        adj[u[i]].pb({v[i], i});
        adj[v[i]].pb({u[i], i});
    }
    dfs(0, -1);
    w.assign(m, 1);
    max_cost = ask(w);
    w.assign(m, 0);
    s = flat[go(1, n - 1, max_cost)];
    w.assign(m, 0);
    timer = 0;
    dfs(s, -1);
    t = flat[go(1, n - 1, max_cost)];
    assert(s >= 0 && s < n && t >= 0 && t < n);
    answer(s, t);
    return;
}

Compilation message (stderr)

highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:41:15: warning: unused variable 'l' [-Wunused-variable]
     int i, m, l, r, mid, s, t;
               ^
highway.cpp:41:18: warning: unused variable 'r' [-Wunused-variable]
     int i, m, l, r, mid, s, t;
                  ^
highway.cpp:41:21: warning: unused variable 'mid' [-Wunused-variable]
     int i, m, l, r, mid, s, t;
                     ^~~

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