Submission #1009987

#	Time	Username	Problem	Language	Result	Execution time	Memory
1009987		boris_mihov	Overtaking (IOI23_overtaking)	C++17	39 / 100	3564 ms	31356 KiB

overtaking

#include "overtaking.h"
#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>

typedef long long llong;
const int MAXN = 1000 + 10;
const int MAXQ = 5000 + 10;

llong x;
int n, m, l;
std::vector <int> s;
std::vector <std::pair <llong,int>> buses;
std::vector <std::pair <llong,llong>> t[MAXN];
std::vector <llong> ifBegining[MAXN];

int findIntersection(int pos, llong time)
{
    int l = 0, r = t[pos].size(), mid;
    while (l < r - 1)
    {
        mid = l + r >> 1;
        if (t[pos][mid].first < time) l = mid;
        else r = mid;
    }

    return l;
}

long long my_arrival_time(int pos, llong time)
{
    for (int i = pos ; i + 1 < m ; ++i)
    {
        int l = 0, r = t[i].size(), mid;
        while (l < r - 1)
        {
            mid = l + r >> 1;
            if (t[i][mid].first < time) l = mid;
            else r = mid;
        }   

        time = std::max(time + 1LL * x * (s[i + 1] - s[i]), t[i][l].second);
    }

    return time;
}

void init(int L, int N, std::vector <long long> T, std::vector <int> W, int X, int M, std::vector <int> S)
{
    n = N;
    m = M;
    s = S;
    x = X;

    for (int i = 0 ; i < n ; ++i)
    {
        buses.push_back({T[i], W[i]});
    }

    for (int i = 0 ; i + 1 < m ; ++i)
    {
        t[i].push_back({-1, 0});
        std::vector <std::pair <llong,int>> newBuses;
        std::sort(buses.begin(), buses.end());
        for (const auto &[time, w] : buses)
        {
            llong arrive = 1LL * (s[i + 1] - s[i]) * w + time;
            if (arrive > t[i].back().second)
            {
                t[i].push_back({time, arrive});
            }

            newBuses.push_back({t[i].back().second, w});
        }

        buses = newBuses;
    }

    std::vector <std::pair <int,int>> v;
    for (int i = 0 ; i + 1 < m ; ++i)
    {
        for (int j = 1 ; j < t[i].size() ; ++j)
        {
            v.push_back({i, j});
        }
    }

    std::sort(v.begin(), v.end(), [&](auto &a, auto &b)
    {
        return t[a.first][a.second].second - 1LL * s[a.first + 1] * x > t[b.first][b.second].second - 1LL * s[b.first + 1] * x;
    });

    for (int i = 0 ; i + 1 < m ; ++i)
    {
        ifBegining[i].resize(t[i].size());
    }

    for (const auto &[i, j] : v)
    {
        bool done = false;
        ifBegining[i][j] = 1LL * (s[m - 1] - s[i + 1]) * x + t[i][j].second;
        for (int u = i + 1 ; u + 1 < m && !done ; ++u)
        {
            for (int v = 1 ; v < t[u].size() ; ++v)
            {
                if (t[i][j].second - 1LL * s[i + 1] * x > t[u][v].first - 1LL * s[u] * x &&
                    t[i][j].second - 1LL * s[i + 1] * x < t[u][v].second - 1LL * s[u + 1] * x)
                {
                    ifBegining[i][j] = std::max(ifBegining[i][j], ifBegining[u][v]);
                    done = true;
                }
            }
        }

        assert(ifBegining[i][j] == my_arrival_time(i + 1, t[i][j].second));
    }

}

long long arrival_time(llong time)
{
    for (int i = 0 ; i + 1 < m ; ++i)
    {
        int l = 0, r = t[i].size(), mid;
        while (l < r - 1)
        {
            mid = l + r >> 1;
            if (t[i][mid].first < time) l = mid;
            else r = mid;
        }   

        if (l != 0 && time + 1LL * x * (s[i + 1] - s[i]) < t[i][l].second)
        {
            return ifBegining[i][l];
        }

        time += 1LL * x * (s[i + 1] - s[i]);
    }

    return time;
}

Compilation message (stderr)

overtaking.cpp: In function 'int findIntersection(int, llong)':
overtaking.cpp:24:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   24 |         mid = l + r >> 1;
      |               ~~^~~
overtaking.cpp: In function 'long long int my_arrival_time(int, llong)':
overtaking.cpp:39:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   39 |             mid = l + r >> 1;
      |                   ~~^~~
overtaking.cpp: In function 'void init(int, int, std::vector<long long int>, std::vector<int>, int, int, std::vector<int>)':
overtaking.cpp:84:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   84 |         for (int j = 1 ; j < t[i].size() ; ++j)
      |                          ~~^~~~~~~~~~~~~
overtaking.cpp:106:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |             for (int v = 1 ; v < t[u].size() ; ++v)
      |                              ~~^~~~~~~~~~~~~
overtaking.cpp: In function 'long long int arrival_time(llong)':
overtaking.cpp:129:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
  129 |             mid = l + r >> 1;
      |                   ~~^~~

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