Submission #1220948

#	Time	Username	Problem	Language	Result	Execution time	Memory
1220948		PotatoMan	Overtaking (IOI23_overtaking)	C++17	0 / 100	0 ms	324 KiB

overtaking

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

typedef long long ll;

struct Bus {
    ll arrivalTime;
    ll pace;
    int id;
};

bool byArrivalThenPace(const Bus &a, const Bus &b) {
    if (a.arrivalTime == b.arrivalTime) return a.pace < b.pace;
    return a.arrivalTime < b.arrivalTime;
}

vector<Bus> buses;
vector<Bus> buses_init;        // initial state for reset
vector<int> stations;
int N, M;

vector<ll> arrivalTimes_station[1005];  // per station sorted arrival times of buses

ll computeExpectedArrival(const Bus& b, int j) {
    return b.arrivalTime + (stations[j] - stations[j - 1]) * b.pace;
}

void init(int Lp, int Np, vector<ll> Tp, vector<int> Wp, int Xp, int Mp, vector<int> Sp) {
    buses.clear();
    stations = Sp;

    // Keep only buses with pace >= reserve pace Xp (filtering)
    for (int i = 0; i < Np; i++) {
        if (Wp[i] >= Xp)
            buses.push_back({Tp[i], Wp[i], i});
    }

    // Add reserve bus with arrivalTime=0 (will set real departure time per query)
    buses.push_back({0, Xp, (int)Np});
    N = (int)buses.size();
    M = Mp;

    // Save initial state for reset before queries
    buses_init = buses;

    // Simulate station by station
    for (int j = 1; j < M; j++) {
        sort(buses.begin(), buses.end(), byArrivalThenPace);

        ll curMax = 0;
        vector<ll> arrivalTimes;
        arrivalTimes.reserve(N);

        for (int i = 0; i < N; i++) {
            ll expected = computeExpectedArrival(buses[i], j);
            buses[i].arrivalTime = max(expected, curMax);
            curMax = max(curMax, buses[i].arrivalTime);
            arrivalTimes.push_back(buses[i].arrivalTime);
        }

        arrivalTimes_station[j] = arrivalTimes;
    }
}

ll arrival_time(ll Y) {
    // Reset buses to initial state
    buses = buses_init;

    ll arrival = Y;
    ll pace = 0;

    // Set reserve bus departure time & get pace
    for (auto &b : buses) {
        if (b.id == N - 1) {
            b.arrivalTime = Y;
            pace = b.pace;
            break;
        }
    }

    // Simulate reserve bus arrival through stations with binary search
    for (int j = 1; j < M; j++) {
        const vector<ll>& arrTimes = arrivalTimes_station[j];

        int pos = int(upper_bound(arrTimes.begin(), arrTimes.end(), arrival) - arrTimes.begin());
        ll blockingArrival = (pos == 0) ? 0 : arrTimes[pos - 1];

        ll dist = stations[j] - stations[j - 1];
        arrival = max(arrival + dist * pace, blockingArrival);

        // Update reserve bus arrival time in buses vector
        for (auto &b : buses) {
            if (b.id == N - 1) {
                b.arrivalTime = arrival;
                break;
            }
        }
    }

    // Return final arrival time of reserve bus
    for (const auto &b : buses) {
        if (b.id == N - 1)
            return b.arrivalTime;
    }

    return -1;  // Should never happen
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 9
• Subtask 2: 0 / 10
• Subtask 3: 0 / 20
• Subtask 4: 0 / 26
• Subtask 5: 0 / 35