Submission #547017

#	Time	Username	Problem	Language	Result	Execution time	Memory
547017		fvogel499	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	1349 ms	137024 KiB

railroad

/*
 * File created on 04/08/2022 at 21:58:56.
 * Link to problem: 
 * Description: 
 * Time complexity: O()
 * Space complexity: O()
 * Status: ---
 * Copyright: Ⓒ 2022 Francois Vogel
*/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <functional>

using namespace std;
using namespace __gnu_pbds;

#define mp pair<int, pii>
#define pii pair<int, int>
#define f first
#define s second

#define vi vector<int>
#define all(x) x.begin(), x.end()
#define size(x) (int)((x).size())
#define pb push_back
#define ins insert
#define cls clear

#define int ll
#define ll long long
#define ld long double

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

int* par;

int gp(int x) {
    return par[x] == x ? x : par[x] = gp(par[x]);
}

void merge(int x, int y) {
    x = gp(x);
    y = gp(y);
    if (x == y) return;
    par[y] = x;
}

int plan_roller_coaster_act(vi from, vi to) {
    set<int> av;
    for (int i : from) av.ins(i);
    for (int i : to) av.ins(i);
    map<int, int> compress;
    int kc = 0;
    for (int i : av) compress[i] = kc++;
    map<int, int> decompress;
    for (auto i : compress) decompress[i.s] = i.f;
    for (int i = 0; i < size(from); i++) from[i] = compress[from[i]];
    for (int i = 0; i < size(to); i++) to[i] = compress[to[i]];
    int n = size(compress);
    vi graph [n];
    vi revG [n];
    for (int i = 0; i < size(from); i++) {
        graph[from[i]].pb(to[i]);
        revG[to[i]].pb(from[i]);
    }
    int res = 0;
    int sum = 0;
    for (int i = 0; i < n-1; i++) {
        sum += size(graph[i])-size(revG[i]);
        if (sum > 1) {
            res += (sum-1LL)*(decompress[i+1]-decompress[i]);
        }
        for (int j = 1; j > sum; j--) {
            sum++;
            graph[i].pb(i+1);
            revG[i+1].pb(i);
            break;
        }
        for (int j = 1; j < sum; j++) {
            sum--;
            graph[i+1].pb(i);
            revG[i].pb(i+1);
            break;
        }
    }
    int comp [n];
    for (int i = 0; i < n; i++) comp[i] = -1;
    int nbComps = 0;
    for (int i = 0; i < n; i++) if (comp[i] == -1) {
        queue<int> q;
        q.push(i);
        comp[i] = nbComps;
        while (!q.empty()) {
            int x = q.front();
            q.pop();
            for (int y : graph[x]) if (comp[y] == -1) {
                comp[y] = nbComps;
                q.push(y);
            }
            for (int y : revG[x]) if (comp[y] == -1) {
                comp[y] = nbComps;
                q.push(y);
            }
        }
        nbComps++;
    }
    vector<mp> edges;
    for (int i = 0; i < n-1; i++) if (comp[i] != comp[i+1]) edges.pb(mp(decompress[i+1]-decompress[i], pii(comp[i], comp[i+1])));
    sort(all(edges));
    par = new int [nbComps];
    for (int i = 0; i < nbComps; i++) par[i] = i;
    for (mp i : edges) if (gp(i.s.f) != gp(i.s.s)) {
        merge(i.s.f, i.s.s);
        res += i.f;
    }
    return res;
}

int plan_roller_coaster(vector<signed> from, vector<signed> to) {
    vi ifrom, ito;
    for (int i : from) ifrom.pb(i);
    for (int i : to) ito.pb(i);
    return plan_roller_coaster_act(ifrom, ito);
}

// signed main() {
//     cin.tie(0);
//     ios_base::sync_with_stdio(0);

//     int n;
//     cin >> n;
//     vector<signed> from(n), to(n);
//     for (int i = 0; i < n; i++) cin >> from[i];
//     for (int i = 0; i < n; i++) cin >> to[i];
//     cout << plan_roller_coaster(from, to) << endl;

//     cout.flush();
//     int d = 0;
//     d++;
// }

• Subtask 1: 11 / 11
• Subtask 2: 23 / 23
• Subtask 3: 30 / 30
• Subtask 4: 36 / 36