最近我一直在iPhone上玩一款名为《Scramble》的游戏。有些人可能知道这个游戏叫拼字游戏。从本质上讲，当游戏开始时，你会得到一个字母矩阵:
F X I E
A M L O
E W B X
A S T U
The goal of the game is to find as many words as you can that can be formed by chaining letters together. You can start with any letter, and all the letters that surround it are fair game, and then once you move on to the next letter, all the letters that surround that letter are fair game, except for any previously used letters. So in the grid above, for example, I could come up with the words LOB, TUX, SEA, FAME, etc. Words must be at least 3 characters, and no more than NxN characters, which would be 16 in this game but can vary in some implementations. While this game is fun and addictive, I am apparently not very good at it and I wanted to cheat a little bit by making a program that would give me the best possible words (the longer the word the more points you get).
(来源:boggled.org)
不幸的是，我不太擅长算法或它们的效率等等。我的第一次尝试使用一个像这样的字典(约2.3MB)，并进行线性搜索，试图匹配字典条目的组合。这需要花费很长时间来找到可能的单词，因为你每轮只有2分钟的时间，这是不够的。
我很有兴趣看看是否有任何Stackoverflowers可以提出更有效的解决方案。我主要是在寻找使用三大p的解决方案:Python、PHP和Perl，尽管任何使用Java或c++的东西也很酷，因为速度是至关重要的。
目前的解决方案:
Adam Rosenfield, Python， ~20岁
John Fouhy, Python， ~3秒
Kent Fredric, Perl， ~1s
Darius Bacon, Python， ~1s
rvarcher, VB。净,~ 1 s
Paolo Bergantino, PHP(实时链接)，~5s(本地~2s)
所以我想添加另一种PHP方法来解决这个问题，因为每个人都喜欢PHP。
我想做一点重构，比如对字典文件使用regexpression匹配，但现在我只是将整个字典文件加载到一个wordList中。
我使用了链表的思想。每个Node都有一个字符值、一个位置值和一个next指针。
location值是我发现两个节点是否连接的方法。
1 2 3 4
11 12 13 14
21 22 23 24
31 32 33 34
所以使用这个网格，如果第一个节点的位置等于第二个节点的位置+/- 1(同一行)，+/- 9,10,11(上下一行)，我就知道两个节点是连接的。
我使用递归进行主搜索。它从wordList中取出一个单词，找到所有可能的起点，然后递归地找到下一个可能的连接，记住它不能去到它已经使用的位置(这就是为什么我添加$notInLoc)。
无论如何，我知道它需要一些重构，并且希望听到关于如何使它更干净的想法，但是它根据我使用的字典文件产生了正确的结果。根据黑板上元音和组合的数量，大约需要3到6秒。我知道，一旦我对字典结果进行预匹配，这将显著减少。
<?php
ini_set('xdebug.var_display_max_depth', 20);
ini_set('xdebug.var_display_max_children', 1024);
ini_set('xdebug.var_display_max_data', 1024);
class Node {
var $loc;
function __construct($value) {
$this->value = $value;
$next = null;
}
}
class Boggle {
var $root;
var $locList = array (1, 2, 3, 4, 11, 12, 13, 14, 21, 22, 23, 24, 31, 32, 33, 34);
var $wordList = [];
var $foundWords = [];
function __construct($board) {
// Takes in a board string and creates all the nodes
$node = new Node($board[0]);
$node->loc = $this->locList[0];
$this->root = $node;
for ($i = 1; $i < strlen($board); $i++) {
$node->next = new Node($board[$i]);
$node->next->loc = $this->locList[$i];
$node = $node->next;
}
// Load in a dictionary file
// Use regexp to elimate all the words that could never appear and load the
// rest of the words into wordList
$handle = fopen("dict.txt", "r");
if ($handle) {
while (($line = fgets($handle)) !== false) {
// process the line read.
$line = trim($line);
if (strlen($line) > 2) {
$this->wordList[] = trim($line);
}
}
fclose($handle);
} else {
// error opening the file.
echo "Problem with the file.";
}
}
function isConnected($node1, $node2) {
// Determines if 2 nodes are connected on the boggle board
return (($node1->loc == $node2->loc + 1) || ($node1->loc == $node2->loc - 1) ||
($node1->loc == $node2->loc - 9) || ($node1->loc == $node2->loc - 10) || ($node1->loc == $node2->loc - 11) ||
($node1->loc == $node2->loc + 9) || ($node1->loc == $node2->loc + 10) || ($node1->loc == $node2->loc + 11)) ? true : false;
}
function find($value, $notInLoc = []) {
// Returns a node with the value that isn't in a location
$current = $this->root;
while($current) {
if ($current->value == $value && !in_array($current->loc, $notInLoc)) {
return $current;
}
if (isset($current->next)) {
$current = $current->next;
} else {
break;
}
}
return false;
}
function findAll($value) {
// Returns an array of nodes with a specific value
$current = $this->root;
$foundNodes = [];
while ($current) {
if ($current->value == $value) {
$foundNodes[] = $current;
}
if (isset($current->next)) {
$current = $current->next;
} else {
break;
}
}
return (empty($foundNodes)) ? false : $foundNodes;
}
function findAllConnectedTo($node, $value, $notInLoc = []) {
// Returns an array of nodes that are connected to a specific node and
// contain a specific value and are not in a certain location
$nodeList = $this->findAll($value);
$newList = [];
if ($nodeList) {
foreach ($nodeList as $node2) {
if (!in_array($node2->loc, $notInLoc) && $this->isConnected($node, $node2)) {
$newList[] = $node2;
}
}
}
return (empty($newList)) ? false : $newList;
}
function inner($word, $list, $i = 0, $notInLoc = []) {
$i++;
foreach($list as $node) {
$notInLoc[] = $node->loc;
if ($list2 = $this->findAllConnectedTo($node, $word[$i], $notInLoc)) {
if ($i == (strlen($word) - 1)) {
return true;
} else {
return $this->inner($word, $list2, $i, $notInLoc);
}
}
}
return false;
}
function findWord($word) {
if ($list = $this->findAll($word[0])) {
return $this->inner($word, $list);
}
return false;
}
function findAllWords() {
foreach($this->wordList as $word) {
if ($this->findWord($word)) {
$this->foundWords[] = $word;
}
}
}
function displayBoard() {
$current = $this->root;
for ($i=0; $i < 4; $i++) {
echo $current->value . " " . $current->next->value . " " . $current->next->next->value . " " . $current->next->next->next->value . "<br />";
if ($i < 3) {
$current = $current->next->next->next->next;
}
}
}
}
function randomBoardString() {
return substr(str_shuffle(str_repeat("abcdefghijklmnopqrstuvwxyz", 16)), 0, 16);
}
$myBoggle = new Boggle(randomBoardString());
$myBoggle->displayBoard();
$x = microtime(true);
$myBoggle->findAllWords();
$y = microtime(true);
echo ($y-$x);
var_dump($myBoggle->foundWords);
?>
如何简单的排序和使用字典中的二进制搜索?
在0.35秒内返回整个列表，并可以进一步优化(例如删除含有未使用字母的单词等)。
from bisect import bisect_left
f = open("dict.txt")
D.extend([line.strip() for line in f.readlines()])
D = sorted(D)
def neibs(M,x,y):
n = len(M)
for i in xrange(-1,2):
for j in xrange(-1,2):
if (i == 0 and j == 0) or (x + i < 0 or x + i >= n or y + j < 0 or y + j >= n):
continue
yield (x + i, y + j)
def findWords(M,D,x,y,prefix):
prefix = prefix + M[x][y]
# find word in dict by binary search
found = bisect_left(D,prefix)
# if found then yield
if D[found] == prefix:
yield prefix
# if what we found is not even a prefix then return
# (there is no point in going further)
if len(D[found]) < len(prefix) or D[found][:len(prefix)] != prefix:
return
# recourse
for neib in neibs(M,x,y):
for word in findWords(M,D,neib[0], neib[1], prefix):
yield word
def solve(M,D):
# check each starting point
for x in xrange(0,len(M)):
for y in xrange(0,len(M)):
for word in findWords(M,D,x,y,""):
yield word
grid = "fxie amlo ewbx astu".split()
print [x for x in solve(grid,D)]
这是我想出的解决填字游戏的办法。我想这是最“python”的做事方式:
from itertools import combinations
from itertools import izip
from math import fabs
def isAllowedStep(current,step,length,doubleLength):
# for step == length -1 not to be 0 => trivial solutions are not allowed
return length > 1 and \
current + step < doubleLength and current - step > 0 and \
( step == 1 or step == -1 or step <= length+1 or step >= length - 1)
def getPairwiseList(someList):
iterableList = iter(someList)
return izip(iterableList, iterableList)
def isCombinationAllowed(combination,length,doubleLength):
for (first,second) in getPairwiseList(combination):
_, firstCoordinate = first
_, secondCoordinate = second
if not isAllowedStep(firstCoordinate, fabs(secondCoordinate-firstCoordinate),length,doubleLength):
return False
return True
def extractSolution(combinations):
return ["".join([x[0] for x in combinationTuple]) for combinationTuple in combinations]
length = 4
text = tuple("".join("fxie amlo ewbx astu".split()))
textIndices = tuple(range(len(text)))
coordinates = zip(text,textIndices)
validCombinations = [combination for combination in combinations(coordinates,length) if isCombinationAllowed(combination,length,length*length)]
solution = extractSolution(validCombinations)
我善意地建议你不要将这部分用于所有可能的匹配，但它实际上提供了一种检查你生成的单词是否真的构成有效单词的可能性:
import mechanize
def checkWord(word):
url = "https://en.oxforddictionaries.com/search?filter=dictionary&query="+word
br = mechanize.Browser()
br.set_handle_robots(False)
response = br.open(url)
text = response.read()
return "no exact matches" not in text.lower()
print [valid for valid in solution[:10] if checkWord(valid)]
