C ++
Lunghezza totale: 9059, Area totale: 27469, Guasti: 13.
Nota: il punteggio include penalità di fallimento.
Uscita campione:
a 6 b 8 c 11 d 11 e 11 f 11 g 12 h 15 i 18 j 18 k 21 l 23 m 26 n 28 o 28 p 30 q 32 r 33 s 33 t 34
------ae
| |
|---c
b||-g
|d|
f |
i---|
k---| h
| j
|---m
l | t
o-n|
|s-r
|-|
p q
Length: 39, Area: 150.
a 6 b 6 c 6 d 6 e 6 f 6 g 6 h 8 i 9 j 9 k 9 l 12 m 12 n 13 o 14 p 15 q 15 r 15 s 17 t 17 u 17 v 17 w 17 x 20 y 23 z 26
------a n|--w
|d-||---k|-o|
| g|b |--m --x
|-|c ||--r|
||f l|-q |
||--j u--|--s|-
e|-i |p| y|
h v t z-
Length: 56, Area: 120.
Uscita completa: http://pastebin.com/raw.php?i=spBUidBV
Non ti piacciono le soluzioni a forza bruta? Questo è un po 'più di un semplice algoritmo di backtracking: il nostro instancabile lavoratore si sposta sulla mappa, posizionando micce e fuochi d'artificio, se necessario, testando tutte le possibili mosse in qualsiasi momento. Bene, quasi --- limitiamo l'insieme di mosse e abbandoniamo precocemente gli stati non ottimali in modo che non ci voglia insopportabilmente lungo (e, in particolare, in modo che termini). Si presta particolare attenzione a non creare cicli o involontari percorsi e di non tornare allo stesso modo in cui siamo venuti, quindi è garantito che non visiteremo lo stesso stato due volte. Anche così, trovare una soluzione ottimale può richiedere del tempo, quindi alla fine rinunciamo a ottimizzare una soluzione se impiega troppo tempo.
Questo algoritmo ha ancora qualche margine. Per prima cosa, è possibile trovare soluzioni migliori aumentando i FRUSTRATIONparametri. Non c'è un bancomat della concorrenza, ma questi numeri possono essere aumentati se e quando ...
Compilare con: g++ fireworks.cpp -ofireworks -std=c++11 -pthread -O3.
Corri con: ./fireworks.
Legge l'input da STDIN e scrive l'output su STDOUT (possibilmente non funzionante).
/* Magic numbers */
#define THREAD_COUNT 2
/* When FRUSTRATION_MOVES moves have passed since the last solution was found,
* the last (1-FRUSTRATION_STATES_BACKOFF)*100% of the backtracking states are
* discarded and FRUSTRATION_MOVES is multiplied by FRUSTRATION_MOVES_BACKOFF.
* The lower these values are, the faster the algorithm is going to give up on
* searching for better solutions. */
#define FRUSTRATION_MOVES 1000000
#define FRUSTRATION_MOVES_BACKOFF 0.8
#define FRUSTRATION_STATES_BACKOFF 0.5
#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
#include <thread>
#include <mutex>
#include <string>
#include <sstream>
#include <cassert>
using namespace std;
/* A tile on the board. Either a fuse, a firework, an empty tile or an
* out-of-boudns tile. */
struct tile {
/* The tile's value, encoded the "obvious" way (i.e. '-', '|', 'a', etc.)
* Empty tiles are encoded as '\0' and OOB tiles as '*'. */
char value;
/* For fuse tiles, the time at which the fuse is lit. */
int time;
operator char&() { return value; }
operator const char&() const { return value; }
bool is_fuse() const { return value == '-' || value == '|'; }
/* A tile is vacant if it's empty or OOB. */
bool is_vacant() const { return !value || value == '*'; }
/* Prints the tile. */
template <typename C, typename T>
friend basic_ostream<C, T>& operator<<(basic_ostream<C, T>& os,
const tile& t) {
return os << (t.value ? t.value : ' ');
}
};
/* Fireworks have the same encoding as tiles. */
typedef tile firework;
typedef vector<firework> fireworks;
/* The fuse map. It has physical dimensions (its bounding-box) but is
* conceptually infinite (filled with empty tiles.) */
class board {
/* The tiles, ordered left-to-right top-to-bottom. */
vector<tile> p_data;
/* The board dimensions. */
int p_width, p_height;
/* The total fuse length. */
int p_length;
public:
board(): p_width(0), p_height(0), p_length(0) {}
/* Physical dimensions. */
int width() const { return p_width; }
int height() const { return p_height; }
int area() const { return width() * height(); }
/* Total fuse length. */
int length() const { return p_length; }
/* Returns the tile at (x, y). If x or y are negative, returns an OOB
* tile. */
tile get(int x, int y) const {
if (x < 0 || y < 0)
return {'*'};
else if (x >= width() || y >= height())
return {'\0'};
else
return p_data[y * width() + x];
}
/* Sets the tile at (x, y). x and y must be nonnegative and the tile at
* (x, y) must be empty. */
board& set(int x, int y, const tile& t) & {
assert(x >= 0 && y >= 0);
assert(!get(x, y));
if (x >= width() || y >= height()) {
int new_width = x >= width() ? x + 1 : width();
int new_height = y >= height() ? y + 1 : height();
vector<tile> temp(new_width * new_height, {'\0'});
for (int l = 0; l < height(); ++l)
copy(
p_data.begin() + l * width(),
p_data.begin() + (l + 1) * width(),
temp.begin() + l * new_width
);
p_data.swap(temp);
p_width = new_width;
p_height = new_height;
}
p_data[y * width() + x] = t;
if (t.is_fuse())
++p_length;
return *this;
}
board&& set(int x, int y, const tile& t) && { return move(set(x, y, t)); }
/* Prints the board. */
template <typename C, typename T>
friend basic_ostream<C, T>& operator<<(basic_ostream<C, T>& os,
const board& b) {
for (int y = 0; y < b.height(); ++y) {
for (int x = 0; x < b.width(); ++x)
os << b.get(x, y);
os << endl;
}
return os;
}
};
/* A state of the tiling algorithm. */
struct state {
/* The current board. */
board b;
/* The next firework to tile. */
fireworks::const_iterator fw;
/* The current location. */
int x, y;
/* The current movement direction. 'N'orth 'S'outh 'E'ast, 'W'est or
* 'A'ny. */
char dir;
};
/* Adds a state to the state-stack if its total fuse length and bounding-box
* area are not worse than the current best ones. */
void add_state(vector<state>& states, int max_length, int max_area,
state&& new_s) {
if (new_s.b.length() < max_length ||
(new_s.b.length() == max_length && new_s.b.area() <= max_area)
)
states.push_back(move(new_s));
}
/* Adds the state after moving in a given direction, if it's a valid move. */
void add_movement(vector<state>& states, int max_length, int max_area,
const state& s, char dir) {
int x = s.x, y = s.y;
char parallel_fuse;
switch (dir) {
case 'E': if (s.dir == 'W') return; ++x; parallel_fuse = '|'; break;
case 'W': if (s.dir == 'E') return; --x; parallel_fuse = '|'; break;
case 'S': if (s.dir == 'N') return; ++y; parallel_fuse = '-'; break;
case 'N': if (s.dir == 'S') return; --y; parallel_fuse = '-'; break;
}
const tile t = s.b.get(s.x, s.y), nt = s.b.get(x, y);
assert(t.is_fuse());
if (nt.is_fuse() && !(t == parallel_fuse && nt == parallel_fuse))
add_state(states, max_length, max_area, {s.b, s.fw, x, y, dir});
}
/* Adds the state after moving in a given direction and tiling a fuse, if it's a
* valid move. */
void add_fuse(vector<state>& states, int max_length, int max_area,
const state& s, char dir, char fuse) {
int x = s.x, y = s.y;
int sgn;
bool horz;
switch (dir) {
case 'E': ++x; sgn = 1; horz = true; break;
case 'W': --x; sgn = -1; horz = true; break;
case 'S': ++y; sgn = 1; horz = false; break;
case 'N': --y; sgn = -1; horz = false; break;
}
if (s.b.get(x, y))
/* Tile is not empty. */
return;
/* Make sure we don't create cycles or reconnect a firework. */
const tile t = s.b.get(s.x, s.y);
assert(t.is_fuse());
if (t == '-') {
if (horz) {
if (fuse == '-') {
if (!s.b.get(x + sgn, y).is_vacant() ||
s.b.get(x, y - 1) == '|' ||
s.b.get(x, y + 1) == '|')
return;
} else {
if (s.b.get(x + sgn, y) == '-' ||
!s.b.get(x, y - 1).is_vacant() ||
!s.b.get(x, y + 1).is_vacant())
return;
}
} else {
if (!s.b.get(x, y + sgn).is_vacant() ||
s.b.get(x - 1, y) == '-' ||
s.b.get(x + 1, y) == '-')
return;
}
} else {
if (!horz) {
if (fuse == '|') {
if (!s.b.get(x, y + sgn).is_vacant() ||
s.b.get(x - 1, y) == '-' ||
s.b.get(x + 1, y) == '-')
return;
} else {
if (s.b.get(x, y + sgn) == '|' ||
!s.b.get(x - 1, y).is_vacant() ||
!s.b.get(x + 1, y).is_vacant())
return;
}
} else {
if (!s.b.get(x + sgn, y).is_vacant() ||
s.b.get(x, y - 1) == '|' ||
s.b.get(x, y + 1) == '|')
return;
}
}
/* Ok. */
add_state(
states,
max_length,
max_area,
{board(s.b).set(x, y, {fuse, t.time + 1}), s.fw, x, y, dir}
);
}
/* Adds the state after adding a firework at the given direction, if it's a
* valid move. */
void add_firework(vector<state>& states, int max_length, int max_area,
const state& s, char dir) {
int x = s.x, y = s.y;
int sgn;
bool horz;
switch (dir) {
case 'E': ++x; sgn = 1; horz = true; break;
case 'W': --x; sgn = -1; horz = true; break;
case 'S': ++y; sgn = 1; horz = false; break;
case 'N': --y; sgn = -1; horz = false; break;
}
if (s.b.get(x, y))
/* Tile is not empty. */
return;
/* Make sure we don't run into an undeliberate fuse. */
if (horz) {
if (s.b.get(x + sgn, y) == '-' || s.b.get(x, y - 1) == '|' ||
s.b.get(x, y + 1) == '|')
return;
} else {
if (s.b.get(x, y + sgn) == '|' || s.b.get(x - 1, y) == '-' ||
s.b.get(x + 1, y) == '-')
return;
}
/* Ok. */
add_state(
states,
max_length,
max_area,
/* After adding a firework, we can move in any direction. */
{board(s.b).set(x, y, {*s.fw}), s.fw + 1, s.x, s.y, 'A'}
);
}
void add_possible_moves(vector<state>& states, int max_length, int max_area,
const state& s) {
/* We add the new states in reverse-desirability order. The most
* (aesthetically) desirable states are added last. */
const tile t = s.b.get(s.x, s.y);
assert(t.is_fuse());
/* Move in all (possible) directions. */
for (char dir : "WENS")
if (dir) add_movement(states, max_length, max_area, s, dir);
/* If the fuse is too short for the next firework, keep adding fuse. */
if (t.time < s.fw->time) {
if (t == '-') {
add_fuse(states, max_length, max_area, s, 'N', '|');
add_fuse(states, max_length, max_area, s, 'S', '|');
add_fuse(states, max_length, max_area, s, 'W', '|');
add_fuse(states, max_length, max_area, s, 'W', '-');
add_fuse(states, max_length, max_area, s, 'E', '|');
add_fuse(states, max_length, max_area, s, 'E', '-');
} else {
add_fuse(states, max_length, max_area, s, 'W', '-');
add_fuse(states, max_length, max_area, s, 'E', '-');
add_fuse(states, max_length, max_area, s, 'N', '-');
add_fuse(states, max_length, max_area, s, 'N', '|');
add_fuse(states, max_length, max_area, s, 'S', '-');
add_fuse(states, max_length, max_area, s, 'S', '|');
}
} else if (t.time == s.fw->time) {
/* If we have enough fuse for the next firework, place the firework (if
* possible) and don't add more fuse, or else we'll never finish... */
if (t == '-') {
add_firework(states, max_length, max_area, s, 'W');
add_firework(states, max_length, max_area, s, 'E');
} else {
add_firework(states, max_length, max_area, s, 'N');
add_firework(states, max_length, max_area, s, 'S');
}
}
}
void thread_proc(mutex& lock, int& total_length, int& total_area,
int& failures) {
fireworks fw;
vector<state> states;
while (true) {
/* Read input. */
string input;
{
lock_guard<mutex> lg(lock);
while (!cin.eof() && input.empty())
getline(cin, input);
if (input.empty())
break;
}
fw.clear();
int length = 0, area;
{
stringstream is;
is << input;
while (!is.eof()) {
char c;
int t;
if (is >> c >> t) {
/* Fireworks must be sorted by launch time. */
assert(fw.empty() || t >= fw.back().time);
fw.push_back({c, t});
length += t;
}
}
assert(!fw.empty());
area = fw.back().time * fw.back().time;
}
/* Add initial state. */
states.push_back({board().set(0, 0, {'-', 1}), fw.begin(), 0, 0, 'A'});
board solution;
int moves = 0;
int frustration_moves = FRUSTRATION_MOVES;
while (!states.empty()) {
/* Check for solutions (all fireworks consumed.) */
while (!states.empty() && states.back().fw == fw.end()) {
state& s = states.back();
/* Did we find a better solution? */
if (solution.area() == 0 || s.b.length() < length ||
(s.b.length() == length && s.b.area() < area)
) {
solution = move(s.b);
moves = 0;
length = solution.length();
area = solution.area();
}
states.pop_back();
}
/* Expand the top state. */
if (!states.empty()) {
state s = move(states.back());
states.pop_back();
add_possible_moves(states, length, area, s);
}
/* Getting frustrated? */
++moves;
if (moves > frustration_moves) {
/* Get rid of some data. */
states.erase(
states.begin() + states.size() * FRUSTRATION_STATES_BACKOFF,
states.end()
);
frustration_moves *= FRUSTRATION_MOVES_BACKOFF;
moves = 0;
}
}
/* Print solution. */
{
lock_guard<mutex> lg(lock);
cout << input << endl;
if (solution.area())
cout << solution;
else {
cout << "FAILED!" << endl;
++failures;
}
cout << "Length: " << length <<
", Area: " << area <<
"." << endl << endl;
total_length += length;
total_area += area;
}
}
}
int main(int argc, const char* argv[]) {
thread threads[THREAD_COUNT];
mutex lock;
int total_length = 0, total_area = 0, failures = 0;
for (int i = 0; i < THREAD_COUNT; ++i)
threads[i] = thread(thread_proc, ref(lock), ref(total_length),
ref(total_area), ref(failures));
for (int i = 0; i < THREAD_COUNT; ++i)
threads[i].join();
cout << "Total Length: " << total_length <<
", Total Area: " << total_area <<
", Failures: " << failures <<
"." << endl;
}
Pitone
Lunghezza totale: 17387, Area totale: 62285, Guasti: 44.
Uscita campione:
a 6 b 8 c 11 d 11 e 11 f 11 g 12 h 15 i 18 j 18 k 21 l 23 m 26 n 28 o 28 p 30 q 32 r 33 s 33 t 34
------a
|----f
|---c
b|||---h
|dg |
e |-j
|---k
i |
|---m
l |-o
|--p
n |--s
|-r
q|
t
Length: 45, Area: 345.
Uscita completa: http://pastebin.com/raw.php?i=mgiqXCRK
Per riferimento, ecco un approccio molto più semplice. Cerca di collegare i fuochi d'artificio a un'unica linea di fusibili principale, creando una forma a "scala". Se un fuoco d'artificio non riesce a collegarsi direttamente alla linea principale (cosa che accade quando due o più fuochi d'artificio si accendono contemporaneamente) rintraccia la linea principale cercando un punto in cui può diramarsi perpendicolarmente verso il basso o verso destra (e fallisce se non esiste questo punto).
Non sorprende che faccia peggio del solutore della forza bruta, ma non con un margine enorme . Onestamente, mi aspettavo che la differenza fosse un po 'più grande.
Corri con: python fireworks.py.
from __future__ import print_function
import sys
total_length = total_area = failures = 0
for line in sys.stdin:
# Read input.
line = line.strip()
if line == "": continue
fws = line.split(' ')
# The fireworks are a list of pairs of the form (<letter>, <time>).
fws = [(fws[i], int(fws[i + 1])) for i in xrange(0, len(fws), 2)]
# The board is a dictionary of the form <coord>: <tile>.
# The first tile marks the "starting point" and is out-of-bounds.
board = {(-1, 0): '*'}
# The tip of the main "staircase" fuse.
tip_x, tip_y = -1, 0
tip_time = 0
# We didn't fail. Yet...
failed = False
for (fw, fw_time) in fws:
dt = fw_time - tip_time
# Can we add the firework to the main fuse line?
if dt > 0:
# We can. Alternate the direction to create a "staircase" pattern.
if board[(tip_x, tip_y)] == '-': dx, dy = 0, 1; fuse = '|'
else: dx, dy = 1, 0; fuse = '-'
x, y = tip_x, tip_y
tip_x += dt * dx
tip_y += dt * dy
tip_time += dt
else:
# We can't. Trace the main fuse back until we find a point where we
# can thread, or fail if we reach the starting point.
x, y = tip_x, tip_y
while board[(x, y)] != '*':
horz = board[(x, y)] == '-'
if horz: dx, dy = 0, 1; fuse = '|'
else: dx, dy = 1, 0; fuse = '-'
if dt > 0 and (x + dx, y + dy) not in board: break
if horz: x -= 1
else: y -= 1
dt += 1
if board[(x, y)] == '*':
failed = True
break
# Add the fuse and firework.
for i in xrange(dt):
x += dx; y += dy
board[(x, y)] = fuse
board[(x + dx, y + dy)] = fw
# Print output.
print(line)
if not failed:
max_x, max_y = (max(board, key=lambda p: p[i])[i] + 1 for i in (0, 1))
for y in xrange(max_y):
for x in xrange(max_x):
print(board.get((x, y), ' '), end = "")
print()
length = len(board) - len(fws) - 1
area = max_x * max_y
else:
print("FAILED!")
failures += 1
length = sum(map(lambda fw: fw[1], fws))
area = fws[-1][1] ** 2
print("Length: %d, Area: %d.\n" % (length, area))
total_length += length; total_area += area
print("Total Length: %d, Total Area: %d, Failures: %d." %
(total_length, total_area, failures))