| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 1288468 | dashka | Tram (CEOI13_tram) | C++20 | 0 ms | 0 KiB |
// CEOI 2013 - Task: Tram - Solution
// Author: Luka Kalinovcic
#include <cstdio>
#include <map>
#include <set>
#include <vector>
using namespace std;
typedef long long llint;
llint const oo = 1000000000000000000LL;
struct Point {
int r, c;
Point() : r(0), c(0) {}
Point(int r, int c) : r(r), c(c) {}
};
llint Dist(Point const& A, Point const& B) {
llint dr = A.r - B.r;
llint dc = A.c - B.c;
return dr * dr + dc * dc;
}
struct Candidate {
Point point;
llint dist;
};
bool operator<(Candidate const& A, Candidate const& B) {
if (A.dist != B.dist) return A.dist > B.dist;
if (A.point.r != B.point.r) return A.point.r < B.point.r;
return A.point.c < B.point.c;
}
struct Segment;
struct Row {
int r;
bool c1_occupied;
bool c2_occupied;
Segment *up, *down;
Row(int r)
: r(r), c1_occupied(false), c2_occupied(false),
up(NULL), down(NULL) {}
};
struct Segment {
Row* row1, *row2;
Candidate best_seat;
Segment(Row* row1, Row* row2)
: row1(row1),
row2(row2) {
ResetBestSeat();
row1->down = this;
row2->up = this;
}
void ResetBestSeat() {
best_seat.point = Point(row1->r, 1);
best_seat.dist = 0;
}
void FindBestSeat() {
ResetBestSeat();
vector<Point> occupied;
int r1 = row1->r;
int r2 = row2->r;
if (row1->c1_occupied) occupied.push_back(Point(r1, 1));
if (row1->c2_occupied) occupied.push_back(Point(r1, 2));
if (row2->c1_occupied) occupied.push_back(Point(r2, 1));
if (row2->c2_occupied) occupied.push_back(Point(r2, 2));
vector<Point> candidates;
candidates.push_back(Point(r1, 1));
candidates.push_back(Point(r1, 2));
candidates.push_back(Point((r1 + r2) / 2, 1));
candidates.push_back(Point((r1 + r2) / 2, 2));
candidates.push_back(Point((r1 + r2 + 1) / 2, 1));
candidates.push_back(Point((r1 + r2 + 1) / 2, 2));
candidates.push_back(Point(r2, 1));
candidates.push_back(Point(r2, 2));
for (int i = 0; i < (int)candidates.size(); ++i) {
Candidate seat;
seat.point = candidates[i];
seat.dist = oo;
for (int j = 0; j < (int)occupied.size(); ++j) {
llint dist = Dist(candidates[i], occupied[j]);
if (dist < seat.dist) seat.dist = dist;
}
if (seat < best_seat) best_seat = seat;
}
}
};
struct BestSeatCmp {
bool operator()(Segment* seg1, Segment* seg2) {
if (seg1->best_seat < seg2->best_seat) return true;
if (seg2->best_seat < seg1->best_seat) return false;
return seg1->row1->r < seg2->row1->r;
}
};
map<int, Row*> rows;
set<Segment*, BestSeatCmp> segments;
void UpdateSegment(Segment* seg) {
if (!seg) return;
segments.erase(seg);
seg->FindBestSeat();
segments.insert(seg);
}
void DeleteSegment(Segment* seg) {
if (!seg) return;
segments.erase(seg);
delete seg;
}
int main() {
int N, M;
scanf("%d%d", &N, &M);
rows[1] = new Row(1);
rows[N] = new Row(N);
segments.insert(new Segment(rows[1], rows[N]));
UpdateSegment(rows[1]->down);
vector<Point> points(M);
for (int i = 0; i < M; ++i) {
char op;
scanf(" %c", &op);
if (op == 'E') {
Segment* seg = *segments.begin();
points[i] = seg->best_seat.point;
int r = points[i].r;
int c = points[i].c;
printf("%d %d\n", r, c);
Row* row;
if (rows.count(r)) {
row = rows[r];
} else {
Row* row1 = seg->row1;
Row* row2 = seg->row2;
DeleteSegment(seg);
row = new Row(r);
rows[r] = row;
segments.insert(new Segment(row1, row));
segments.insert(new Segment(row, row2));
}
if (c == 1) {
row->c1_occupied = true;
} else {
row->c2_occupied = true;
}
UpdateSegment(row->up);
UpdateSegment(row->down);
} else {
int x;
scanf("%d", &x); --x;
int r = points[x].r;
int c = points[x].c;
Row* row = rows[r];
if (c == 1) {
row->c1_occupied = false;
} else {
row->c2_occupied = false;
}
if (r != 1 && r != N && !row->c1_occupied && !row->c2_occupied) {
Row* row1 = row->up->row1;
Row* row2 = row->down->row2;
DeleteSegment(row->up);
DeleteSegment(row->down);
rows.erase(r);
delete row;
segments.insert(new Segment(row1, row2));
UpdateSegment(row1->down);
} else {
UpdateSegment(row->up);
UpdateSegment(row->down);
}
}
}
return 0;
}