Submission #609747

#	Time	Username	Problem	Language	Result	Execution time	Memory
609747		strange420	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	148 ms	24436 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
using namespace std;

#define MAXN 500000

int p[MAXN];
struct info {
    int val;
    int index;
    int edgeType;

    info(int a, int b, int c) {
        val = a;
        index = b;
        edgeType = c;
    }

    bool operator <(const info& x) {
        return val < x.val;
    }
};
struct edge {
    int s; int e; int cost;
    edge(int start, int end, int c) {
        s = start;
        e = end;
        cost = c;
    }

    bool operator <(const edge& x) {
        return cost < x.cost;
    }
};


int find(int x) {
    return p[x] == x ? x : p[x] = find(p[x]);
}

bool merge(int x, int y) {
    x = find(x); y = find(y);
    p[x] = y;
    return x != y;
}

long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
    s.push_back(1e9+1);
    t.push_back(1);
    int n = (int) s.size();

    vector<info> asd;
    for (int i=0; i<n; i++) {
        p[i] = i;
        asd.emplace_back(s[i], i, 1);
        asd.emplace_back(t[i], i, -1);
    }
    sort(asd.begin(), asd.end());

    long long ans = 0;
    vector<edge> edges;
    for (int i=0, diff=0; i<2*n-1; i++) {   // Looking at the next segment (i, i+1)
        diff += asd[i].edgeType;
        ans += 1LL * (asd[i+1].val - asd[i].val) * max(diff, 0);
        edges.emplace_back(asd[i].index, asd[i+1].index, asd[i+1].val - asd[i].val);
        if (diff != 0) {
            merge(asd[i].index, asd[i+1].index);
        }
    }

    sort(edges.begin(), edges.end());
    for (int i=0; i<2*n; i++)
        if (merge(edges[i].s, edges[i].e))
            ans += 1LL * edges[i].cost;

    return ans;
}

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