제출 #916136

#제출 시각아이디문제언어결과실행 시간메모리
916136redstonegamer22추월 (IOI23_overtaking)C++17
19 / 100
3582 ms2252 KiB
#ifndef LOCAL #include "overtaking.h" #endif // LOCAL #ifdef LOCAL #define _GLIBCXX_DEBUG #include <vector> void init(int L, int N, std::vector<long long> T, std::vector<int> W, int X, int M, std::vector<int> S); long long arrival_time(long long Y); #endif // LOCAL #include <bits/stdc++.h> #define int long long using namespace std; const int time_infty = 1e18 + 7; const int nmax = 1000 + 24; const int nmax_bs_step = (1 << 10); struct bus { int start_time; int speed; }; vector<bus> glob_busses; vector<vector<bus>> busses_by_station; vector<vector<int>> endtime_of_bus_by_station; vector<int> stations; int X_init; void precompute_strips() { // pentru fiecare statie, retin autobuzele ca perechi de (timp, viteza) auto busses = glob_busses; sort(busses.begin(), busses.end(), [](bus a, bus b) { if(a.start_time != b.start_time) return a.start_time < b.start_time; return a.speed < b.speed; }); busses_by_station.push_back(busses); // pentru statia 0 for(int i = 0; i + 1 < stations.size(); i++) { int distance = stations[i + 1] - stations[i]; int max_prefix = -1e9; vector<bus> new_busses; vector<int> new_endtime_of_bus; for(auto b : busses) { max_prefix = max(max_prefix, b.start_time + distance * b.speed); new_busses.push_back({max_prefix, b.speed}); new_endtime_of_bus.push_back(max_prefix); } endtime_of_bus_by_station.push_back(new_endtime_of_bus); busses = new_busses; sort(busses.begin(), busses.end(), [](bus a, bus b) { if(a.start_time != b.start_time) return a.start_time < b.start_time; return a.speed < b.speed; }); busses_by_station.push_back(busses); } } struct intervals { int start, end, actual_end; bool operator<(const intervals &other) const { if(start != other.start) return start < other.start; return end < other.end; } bool operator==(const intervals &other) const { return start == other.start && end == other.end; } }; // daca eu ma aflu la timpul Y si Y intre [start, end], atunci // eu voi termina la timpul end la final set<intervals> solution_set; long long arrival_time_fast(long long Y) { // care doar da query in structura curenta a solution_set-ului // si returneaza timpul de sosire solution_set.insert({-time_infty, -time_infty, -time_infty}); solution_set.insert({time_infty, time_infty, time_infty}); // cautam in solution_set intervalul care contine Y auto it = solution_set.lower_bound({Y, time_infty}); if(it == solution_set.begin()) { // nu exista niciun interval care sa contina Y return Y; } intervals interval = *prev(it); if(Y < interval.start || Y > interval.end) { // nu exista niciun interval care sa contina Y return Y; } return interval.actual_end; } long long query_strip(int strip_index, long long Y) { // strip-ul se intinde de la stations[strip_index] la stations[strip_index + 1] // cautam in busses_by_station[strip_index] autobuzul care ma tine in spate // facem o cautare binara pentru ultimul autobuz care (conform comparatorului custom) este // mai mic decat mine const auto& busses = busses_by_station[strip_index]; // O(1) const auto& endtime_of_bus = endtime_of_bus_by_station[strip_index]; // O(1) int ok = -1; for(int step = nmax_bs_step; step >= 1; step /= 2) { while(ok + step < busses.size() && busses[ok + step].start_time < Y) { ok += step; } } if(ok == -1) { // nu exista niciun autobuz care sa ma tina in spate return Y; } if(endtime_of_bus[ok] < Y) { // nu exista niciun autobuz care sa ma tina in spate return Y; } return endtime_of_bus[ok]; } void add_strip(int strip_index) { // adaugam un nou strip in solution_set // practic la final sa dam query(Y) <=> Y' = query_strip(strip_index, Y) si apoi Y'' = arrival_time_fast(Y') set<intervals> new_solution_set; new_solution_set.insert({-time_infty, -time_infty, -time_infty}); // eu o sa observ ca in general un interval merge de la un bus.start_time + 1 pana la // ???? const auto& busses = busses_by_station[strip_index]; // O(1) vector<int> possible_starts; for(auto b : busses) { possible_starts.push_back(b.start_time + 1); } for(auto prev_interval : solution_set) { if(prev_interval.start == -time_infty) continue; if(prev_interval.start == time_infty) continue; possible_starts.push_back(prev_interval.start); } sort(possible_starts.begin(), possible_starts.end()); for(auto start : possible_starts) { // int start = busses[i].start_time + 1; if(start <= new_solution_set.rbegin()->end) continue; // set.rbegin() este un pointer la ultimul element din set // daca ultimul interval pe care l-am calculat se termina inainte de startul nou // inseamna ca si acest start este parte din intervalul vechi int end = start; int total_query_start = arrival_time_fast(query_strip(strip_index, start)); for(int step = (1LL << 60); step >= 1; step /= 2) { int total_query_end = arrival_time_fast(query_strip(strip_index, end + step)); if(total_query_end == total_query_start) { end += step; } } new_solution_set.insert({start, end, total_query_start}); } new_solution_set.insert({time_infty, time_infty, time_infty}); solution_set = new_solution_set; return; } #undef int void init(int L, int N, std::vector<long long> T, std::vector<int> W, int X, int M, std::vector<int> S) { #define int long long // scad X (viteza autobuzului de query) din fiecare viteza de autobuz (W) for(int i = 0; i < N; ++i) { W[i] -= X; } X_init = X; // initialize busses for(int i = 0; i < N; ++i) { bus b; b.start_time = T[i]; b.speed = W[i]; if(W[i] <= 0) continue; // acest autobuz nu afecteaza autobuzul meu! glob_busses.push_back(b); } // initialize stations for(int i = 0; i < M; ++i) { stations.push_back(S[i]); } precompute_strips(); // initialize solution_set for(int i = stations.size() - 2; i >= 0; i--) { add_strip(i); #ifdef LOCAL cerr << "Added strip " << i << endl; for(auto pr : solution_set) { cerr << pr.start << " " << pr.end << " " << pr.actual_end << endl; } for(int wrong_Y = 0; wrong_Y < 10000; wrong_Y++) { long long fast_answer = arrival_time_fast(wrong_Y); long long slow_answer = wrong_Y; for(int j = i; j + 1 < stations.size(); j++) { slow_answer = query_strip(j, slow_answer); } if(fast_answer != slow_answer) { cerr << "wrong_Y: " << wrong_Y << endl; cerr << "Fast: " << fast_answer << endl; cerr << "Slow: " << slow_answer << endl; cerr << endl; assert(!"Not equal"); } } #endif // LOCAL } } long long arrival_time_brut(long long Y) { auto busses = glob_busses; busses.push_back({Y, 0}); // autobuzul meu incepe la timpul Y si are viteza 0 sort(busses.begin(), busses.end(), [](bus a, bus b) { if(a.start_time != b.start_time) return a.start_time < b.start_time; return a.speed < b.speed; }); for(int i = 0; i + 1 < stations.size(); i++) { int distance = stations[i + 1] - stations[i]; int max_prefix = -1e9; vector<bus> new_busses; for(auto b : busses) { max_prefix = max(max_prefix, b.start_time + distance * b.speed); new_busses.push_back({max_prefix, b.speed}); } busses = new_busses; sort(busses.begin(), busses.end(), [](bus a, bus b) { if(a.start_time != b.start_time) return a.start_time < b.start_time; return a.speed < b.speed; }); } for(auto b : busses) { if(b.speed == 0) return b.start_time; } assert(false); // nu se poate ajunge aici } long long arrival_time_slow(long long Y) { // repeatedly use query_strip() for(int strip_index = 0; strip_index + 1 < stations.size(); strip_index++) { Y = query_strip(strip_index, Y); } return Y; } long long arrival_time(long long Y) { long long answer = arrival_time_fast(Y); #ifdef LOCAL cerr << "Fast: " << answer << endl; cerr << "Slow: " << arrival_time_slow(Y) << endl; cerr << "Brut: " << arrival_time_brut(Y) << endl; assert (answer == arrival_time_slow(Y)); assert (answer == arrival_time_brut(Y)); #endif // LOCAL return answer + 1LL * (stations.back() - stations[0]) * X_init; } #ifdef LOCAL #undef int // Grader #include <cassert> #include <cstdio> #include <vector> int main() { int L, N, X, M, Q; assert(5 == scanf("%d %d %d %d %d", &L, &N, &X, &M, &Q)); std::vector<long long> T(N); for (int i = 0; i < N; i++) assert(1 == scanf("%lld", &T[i])); std::vector<int> W(N); for (int i = 0; i < N; i++) assert(1 == scanf("%d", &W[i])); std::vector<int> S(M); for (int i = 0; i < M; i++) assert(1 == scanf("%d", &S[i])); std::vector<long long> Y(Q); for (int i = 0; i < Q; i++) assert(1 == scanf("%lld", &Y[i])); fclose(stdin); init(L, N, T, W, X, M, S); std::vector<long long> res(Q); for (int i = 0; i < Q; i++) res[i] = arrival_time(Y[i]); for (int i = 0; i < Q; i++) printf("%lld\n", res[i]); fclose(stdout); return 0; } #endif // LOCAL

컴파일 시 표준 에러 (stderr) 메시지

overtaking.cpp: In function 'void precompute_strips()':
overtaking.cpp:45:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |  for(int i = 0; i + 1 < stations.size(); i++) {
      |                 ~~~~~~^~~~~~~~~~~~~~~~~
overtaking.cpp: In function 'long long int query_strip(long long int, long long int)':
overtaking.cpp:127:19: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<bus>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  127 |   while(ok + step < busses.size() && busses[ok + step].start_time < Y) {
      |         ~~~~~~~~~~^~~~~~~~~~~~~~~
overtaking.cpp: In function 'long long int arrival_time_brut(long long int)':
overtaking.cpp:262:23: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  262 |  for(int i = 0; i + 1 < stations.size(); i++) {
      |                 ~~~~~~^~~~~~~~~~~~~~~~~
overtaking.cpp: In function 'long long int arrival_time_slow(long long int)':
overtaking.cpp:292:43: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  292 |  for(int strip_index = 0; strip_index + 1 < stations.size(); strip_index++) {
      |                           ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
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