Submission #53739

#	Time	Username	Problem	Language	Result	Execution time	Memory
53739		aome	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	373 ms	89932 KiB

railroad

#include "railroad.h"

#include <bits/stdc++.h>

using namespace std;

const int N = 200005;
const int INF = 1e9;

int par[N * 2], cnt[N * 2];

int find(int u) { return u == par[u] ? u : par[u] = find(par[u]); }

bool join(int u, int v) { u = find(u), v = find(v), par[u] = v; return u != v; }

struct Edge {
    int w, u, v;

    bool operator < (const Edge& rhs) const {
        return w < rhs.w;
    }
};

long long plan_roller_coaster(vector<int> s, vector<int> t) {
    s.push_back(INF), t.push_back(1);
    vector<int> vec;
    for (auto i : s) vec.push_back(i);
    for (auto i : t) vec.push_back(i);
    sort(vec.begin(), vec.end());
    vec.erase(unique(vec.begin(), vec.end()), vec.end());
    int n = s.size(), m = vec.size();
    for (int i = 0; i < m; ++i) par[i] = i;
    for (int i = 0; i < n; ++i) {
        s[i] = lower_bound(vec.begin(), vec.end(), s[i]) - vec.begin();
        t[i] = lower_bound(vec.begin(), vec.end(), t[i]) - vec.begin();
        if (s[i] < t[i]) cnt[s[i]]++, cnt[t[i]]--;
        else cnt[t[i]]--, cnt[s[i]]++;
        join(s[i], t[i]); 
    }
    for (int i = 1; i < m; ++i) cnt[i] += cnt[i - 1];
    long long res = 0;
    for (int i = 0; i < m; ++i) {
        if (cnt[i] < 0) join(i, i + 1);
        if (cnt[i] > 0) {
            join(i, i + 1), res += 1LL * cnt[i] * (vec[i + 1] - vec[i]);
        }
    }
    vector<Edge> edge;
    for (int i = 1; i < m; ++i) edge.push_back({vec[i] - vec[i - 1], i, i - 1});
    sort(edge.begin(), edge.end());
    for (auto i : edge) {
        if (join(i.u, i.v)) res += i.w;
    }
    return res;
}

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