我知道我在派对上迟到了，但我已经实现了，作为编码练习，在几种编程语言(c++， Java, Go, c#， Python, Ruby, JavaScript, Julia, Lua, PHP, Perl)中使用了一个填字器，我认为有人可能会对这些感兴趣，所以我在这里留下了链接: https://github.com/AmokHuginnsson/boggle-solvers

你可以把这个问题分成两部分:

某种搜索算法可以在网格中列举出可能的字符串。 一种测试字符串是否是有效单词的方法。

理想情况下，(2)还应该包括一种测试字符串是否是有效单词前缀的方法——这将允许您精简搜索并节省大量时间。

亚当·罗森菲尔德(Adam Rosenfield)的Trie是(2)的一个解决方案。它很优雅，可能是算法专家的首选，但有了现代语言和现代计算机，我们可能会更懒一点。此外，正如Kent所建议的，我们可以通过丢弃网格中没有字母的单词来减少字典的大小。这是一些蟒蛇:

def make_lookups(grid, fn='dict.txt'):
    # Make set of valid characters.
    chars = set()
    for word in grid:
        chars.update(word)

    words = set(x.strip() for x in open(fn) if set(x.strip()) <= chars)
    prefixes = set()
    for w in words:
        for i in range(len(w)+1):
            prefixes.add(w[:i])

    return words, prefixes

哇;常数时间前缀测试。加载你链接的字典需要几秒钟，但只有几秒钟:-)(注意words <= prefixes)

现在，对于第(1)部分，我倾向于用图表来思考。所以我将创建一个像这样的字典:

graph = { (x, y):set([(x0,y0), (x1,y1), (x2,y2)]), }

例如，graph[(x, y)]是你从位置(x, y)可以到达的坐标集。我还将添加一个虚拟节点None，它将连接到所有东西。

构建它有点笨拙，因为有8个可能的位置，你必须做边界检查。下面是一些相应笨拙的python代码:

def make_graph(grid):
    root = None
    graph = { root:set() }
    chardict = { root:'' }

    for i, row in enumerate(grid):
        for j, char in enumerate(row):
            chardict[(i, j)] = char
            node = (i, j)
            children = set()
            graph[node] = children
            graph[root].add(node)
            add_children(node, children, grid)

    return graph, chardict

def add_children(node, children, grid):
    x0, y0 = node
    for i in [-1,0,1]:
        x = x0 + i
        if not (0 <= x < len(grid)):
            continue
        for j in [-1,0,1]:
            y = y0 + j
            if not (0 <= y < len(grid[0])) or (i == j == 0):
                continue

            children.add((x,y))

这段代码还建立了一个字典映射(x,y)到相应的字符。这让我把一个位置列表转换成一个单词:

def to_word(chardict, pos_list):
    return ''.join(chardict[x] for x in pos_list)

最后，我们进行深度优先搜索。基本程序是:

搜索到达一个特定的节点。 检查到目前为止的路径是否可能是单词的一部分。如果不是，就不要进一步探索这个分支。 检查到目前为止的路径是否是一个单词。如果是，则添加到结果列表中。 探索迄今为止所有孩子未走的路。

Python:

def find_words(graph, chardict, position, prefix, results, words, prefixes):
    """ Arguments:
      graph :: mapping (x,y) to set of reachable positions
      chardict :: mapping (x,y) to character
      position :: current position (x,y) -- equals prefix[-1]
      prefix :: list of positions in current string
      results :: set of words found
      words :: set of valid words in the dictionary
      prefixes :: set of valid words or prefixes thereof
    """
    word = to_word(chardict, prefix)

    if word not in prefixes:
        return

    if word in words:
        results.add(word)

    for child in graph[position]:
        if child not in prefix:
            find_words(graph, chardict, child, prefix+[child], results, words, prefixes)

运行代码如下:

grid = ['fxie', 'amlo', 'ewbx', 'astu']
g, c = make_graph(grid)
w, p = make_lookups(grid)
res = set()
find_words(g, c, None, [], res, w, p)

检查保留区，看看答案。下面是为你的例子找到的单词列表，按大小排序:

 ['a', 'b', 'e', 'f', 'i', 'l', 'm', 'o', 's', 't',
 'u', 'w', 'x', 'ae', 'am', 'as', 'aw', 'ax', 'bo',
 'bu', 'ea', 'el', 'em', 'es', 'fa', 'ie', 'io', 'li',
 'lo', 'ma', 'me', 'mi', 'oe', 'ox', 'sa', 'se', 'st',
 'tu', 'ut', 'wa', 'we', 'xi', 'aes', 'ame', 'ami',
 'ase', 'ast', 'awa', 'awe', 'awl', 'blo', 'but', 'elb',
 'elm', 'fae', 'fam', 'lei', 'lie', 'lim', 'lob', 'lox',
 'mae', 'maw', 'mew', 'mil', 'mix', 'oil', 'olm', 'saw',
 'sea', 'sew', 'swa', 'tub', 'tux', 'twa', 'wae', 'was',
 'wax', 'wem', 'ambo', 'amil', 'amli', 'asem', 'axil',
 'axle', 'bleo', 'boil', 'bole', 'east', 'fame', 'limb',
 'lime', 'mesa', 'mewl', 'mile', 'milo', 'oime', 'sawt',
 'seam', 'seax', 'semi', 'stub', 'swam', 'twae', 'twas',
 'wame', 'wase', 'wast', 'weam', 'west', 'amble', 'awest',
 'axile', 'embox', 'limbo', 'limes', 'swami', 'embole',
 'famble', 'semble', 'wamble']

代码需要(字面上的)几秒钟来加载字典，但其余的在我的机器上是立即完成的。

对于字典加速，有一个通用的转换/过程可以大大减少提前的字典比较。

鉴于上面的网格只包含16个字符，其中一些字符是重复的，您可以通过简单地过滤掉具有不可获取字符的条目来大大减少字典中的总键数。

我认为这是明显的优化，但看到没有人这么做，我就提出来了。

在输入过程中，它将我的字典从20万个键减少到只有2000个键。这至少减少了内存开销，并且这肯定会映射到某个地方的速度增加，因为内存不是无限快的。

Perl实现

我的实现有点头重脚轻，因为我重视能够知道每个提取的字符串的确切路径，而不仅仅是其中的有效性。

我也有一些适应在那里，理论上允许一个网格中有洞的功能，网格有不同大小的线(假设你得到了正确的输入，它以某种方式对齐)。

早期筛选器是我的应用程序中最重要的瓶颈，正如之前怀疑的那样，注释掉了一行从1.5s膨胀到7.5s的代码。

在执行时，它似乎认为所有的个位数都在他们自己的有效单词上，但我很确定这是由于字典文件的工作方式。

它有点臃肿，但至少我重用了cpan中的Tree::Trie

其中有些部分是受到现有实现的启发，有些是我已经想到的。

建设性的批评和改进的方法欢迎(/我注意到他从来没有在CPAN上搜索过一个拼字游戏解决器，但这更有趣)

新标准更新

#!/usr/bin/perl 

use strict;
use warnings;

{

  # this package manages a given path through the grid.
  # Its an array of matrix-nodes in-order with
  # Convenience functions for pretty-printing the paths
  # and for extending paths as new paths.

  # Usage:
  # my $p = Prefix->new(path=>[ $startnode ]);
  # my $c = $p->child( $extensionNode );
  # print $c->current_word ;

  package Prefix;
  use Moose;

  has path => (
      isa     => 'ArrayRef[MatrixNode]',
      is      => 'rw',
      default => sub { [] },
  );
  has current_word => (
      isa        => 'Str',
      is         => 'rw',
      lazy_build => 1,
  );

  # Create a clone of this object
  # with a longer path

  # $o->child( $successive-node-on-graph );

  sub child {
      my $self    = shift;
      my $newNode = shift;
      my $f       = Prefix->new();

      # Have to do this manually or other recorded paths get modified
      push @{ $f->{path} }, @{ $self->{path} }, $newNode;
      return $f;
  }

  # Traverses $o->path left-to-right to get the string it represents.

  sub _build_current_word {
      my $self = shift;
      return join q{}, map { $_->{value} } @{ $self->{path} };
  }

  # Returns  the rightmost node on this path

  sub tail {
      my $self = shift;
      return $self->{path}->[-1];
  }

  # pretty-format $o->path

  sub pp_path {
      my $self = shift;
      my @path =
        map { '[' . $_->{x_position} . ',' . $_->{y_position} . ']' }
        @{ $self->{path} };
      return "[" . join( ",", @path ) . "]";
  }

  # pretty-format $o
  sub pp {
      my $self = shift;
      return $self->current_word . ' => ' . $self->pp_path;
  }

  __PACKAGE__->meta->make_immutable;
}

{

  # Basic package for tracking node data
  # without having to look on the grid.
  # I could have just used an array or a hash, but that got ugly.

# Once the matrix is up and running it doesn't really care so much about rows/columns,
# Its just a sea of points and each point has adjacent points.
# Relative positioning is only really useful to map it back to userspace

  package MatrixNode;
  use Moose;

  has x_position => ( isa => 'Int', is => 'rw', required => 1 );
  has y_position => ( isa => 'Int', is => 'rw', required => 1 );
  has value      => ( isa => 'Str', is => 'rw', required => 1 );
  has siblings   => (
      isa     => 'ArrayRef[MatrixNode]',
      is      => 'rw',
      default => sub { [] }
  );

# Its not implicitly uni-directional joins. It would be more effient in therory
# to make the link go both ways at the same time, but thats too hard to program around.
# and besides, this isn't slow enough to bother caring about.

  sub add_sibling {
      my $self    = shift;
      my $sibling = shift;
      push @{ $self->siblings }, $sibling;
  }

  # Convenience method to derive a path starting at this node

  sub to_path {
      my $self = shift;
      return Prefix->new( path => [$self] );
  }
  __PACKAGE__->meta->make_immutable;

}

{

  package Matrix;
  use Moose;

  has rows => (
      isa     => 'ArrayRef',
      is      => 'rw',
      default => sub { [] },
  );

  has regex => (
      isa        => 'Regexp',
      is         => 'rw',
      lazy_build => 1,
  );

  has cells => (
      isa        => 'ArrayRef',
      is         => 'rw',
      lazy_build => 1,
  );

  sub add_row {
      my $self = shift;
      push @{ $self->rows }, [@_];
  }

  # Most of these functions from here down are just builder functions,
  # or utilities to help build things.
  # Some just broken out to make it easier for me to process.
  # All thats really useful is add_row
  # The rest will generally be computed, stored, and ready to go
  # from ->cells by the time either ->cells or ->regex are called.

  # traverse all cells and make a regex that covers them.
  sub _build_regex {
      my $self  = shift;
      my $chars = q{};
      for my $cell ( @{ $self->cells } ) {
          $chars .= $cell->value();
      }
      $chars = "[^$chars]";
      return qr/$chars/i;
  }

  # convert a plain cell ( ie: [x][y] = 0 )
  # to an intelligent cell ie: [x][y] = object( x, y )
  # we only really keep them in this format temporarily
  # so we can go through and tie in neighbouring information.
  # after the neigbouring is done, the grid should be considered inoperative.

  sub _convert {
      my $self = shift;
      my $x    = shift;
      my $y    = shift;
      my $v    = $self->_read( $x, $y );
      my $n    = MatrixNode->new(
          x_position => $x,
          y_position => $y,
          value      => $v,
      );
      $self->_write( $x, $y, $n );
      return $n;
  }

# go through the rows/collums presently available and freeze them into objects.

  sub _build_cells {
      my $self = shift;
      my @out  = ();
      my @rows = @{ $self->{rows} };
      for my $x ( 0 .. $#rows ) {
          next unless defined $self->{rows}->[$x];
          my @col = @{ $self->{rows}->[$x] };
          for my $y ( 0 .. $#col ) {
              next unless defined $self->{rows}->[$x]->[$y];
              push @out, $self->_convert( $x, $y );
          }
      }
      for my $c (@out) {
          for my $n ( $self->_neighbours( $c->x_position, $c->y_position ) ) {
              $c->add_sibling( $self->{rows}->[ $n->[0] ]->[ $n->[1] ] );
          }
      }
      return \@out;
  }

  # given x,y , return array of points that refer to valid neighbours.
  sub _neighbours {
      my $self = shift;
      my $x    = shift;
      my $y    = shift;
      my @out  = ();
      for my $sx ( -1, 0, 1 ) {
          next if $sx + $x < 0;
          next if not defined $self->{rows}->[ $sx + $x ];
          for my $sy ( -1, 0, 1 ) {
              next if $sx == 0 && $sy == 0;
              next if $sy + $y < 0;
              next if not defined $self->{rows}->[ $sx + $x ]->[ $sy + $y ];
              push @out, [ $sx + $x, $sy + $y ];
          }
      }
      return @out;
  }

  sub _has_row {
      my $self = shift;
      my $x    = shift;
      return defined $self->{rows}->[$x];
  }

  sub _has_cell {
      my $self = shift;
      my $x    = shift;
      my $y    = shift;
      return defined $self->{rows}->[$x]->[$y];
  }

  sub _read {
      my $self = shift;
      my $x    = shift;
      my $y    = shift;
      return $self->{rows}->[$x]->[$y];
  }

  sub _write {
      my $self = shift;
      my $x    = shift;
      my $y    = shift;
      my $v    = shift;
      $self->{rows}->[$x]->[$y] = $v;
      return $v;
  }

  __PACKAGE__->meta->make_immutable;
}

use Tree::Trie;

sub readDict {
  my $fn = shift;
  my $re = shift;
  my $d  = Tree::Trie->new();

  # Dictionary Loading
  open my $fh, '<', $fn;
  while ( my $line = <$fh> ) {
      chomp($line);

 # Commenting the next line makes it go from 1.5 seconds to 7.5 seconds. EPIC.
      next if $line =~ $re;    # Early Filter
      $d->add( uc($line) );
  }
  return $d;
}

sub traverseGraph {
  my $d     = shift;
  my $m     = shift;
  my $min   = shift;
  my $max   = shift;
  my @words = ();

  # Inject all grid nodes into the processing queue.

  my @queue =
    grep { $d->lookup( $_->current_word ) }
    map  { $_->to_path } @{ $m->cells };

  while (@queue) {
      my $item = shift @queue;

      # put the dictionary into "exact match" mode.

      $d->deepsearch('exact');

      my $cword = $item->current_word;
      my $l     = length($cword);

      if ( $l >= $min && $d->lookup($cword) ) {
          push @words,
            $item;    # push current path into "words" if it exactly matches.
      }
      next if $l > $max;

      # put the dictionary into "is-a-prefix" mode.
      $d->deepsearch('boolean');

    siblingloop: foreach my $sibling ( @{ $item->tail->siblings } ) {
          foreach my $visited ( @{ $item->{path} } ) {
              next siblingloop if $sibling == $visited;
          }

          # given path y , iterate for all its end points
          my $subpath = $item->child($sibling);

          # create a new path for each end-point
          if ( $d->lookup( $subpath->current_word ) ) {

             # if the new path is a prefix, add it to the bottom of the queue.
              push @queue, $subpath;
          }
      }
  }
  return \@words;
}

sub setup_predetermined { 
  my $m = shift; 
  my $gameNo = shift;
  if( $gameNo == 0 ){
      $m->add_row(qw( F X I E ));
      $m->add_row(qw( A M L O ));
      $m->add_row(qw( E W B X ));
      $m->add_row(qw( A S T U ));
      return $m;
  }
  if( $gameNo == 1 ){
      $m->add_row(qw( D G H I ));
      $m->add_row(qw( K L P S ));
      $m->add_row(qw( Y E U T ));
      $m->add_row(qw( E O R N ));
      return $m;
  }
}
sub setup_random { 
  my $m = shift; 
  my $seed = shift;
  srand $seed;
  my @letters = 'A' .. 'Z' ; 
  for( 1 .. 4 ){ 
      my @r = ();
      for( 1 .. 4 ){
          push @r , $letters[int(rand(25))];
      }
      $m->add_row( @r );
  }
}

# Here is where the real work starts.

my $m = Matrix->new();
setup_predetermined( $m, 0 );
#setup_random( $m, 5 );

my $d = readDict( 'dict.txt', $m->regex );
my $c = scalar @{ $m->cells };    # get the max, as per spec

print join ",\n", map { $_->pp } @{
  traverseGraph( $d, $m, 3, $c ) ;
};

Arch/执行信息进行比较:

model name      : Intel(R) Core(TM)2 Duo CPU     T9300  @ 2.50GHz
cache size      : 6144 KB
Memory usage summary: heap total: 77057577, heap peak: 11446200, stack peak: 26448
       total calls   total memory   failed calls
 malloc|     947212       68763684              0
realloc|      11191        1045641              0  (nomove:9063, dec:4731, free:0)
 calloc|     121001        7248252              0
   free|     973159       65854762

Histogram for block sizes:
  0-15         392633  36% ==================================================
 16-31          43530   4% =====
 32-47          50048   4% ======
 48-63          70701   6% =========
 64-79          18831   1% ==
 80-95          19271   1% ==
 96-111        238398  22% ==============================
112-127          3007  <1% 
128-143        236727  21% ==============================

关于正则表达式优化的更多嘟囔

我使用的正则表达式优化对于多解字典是无用的，而对于多解字典，您将需要一个完整的字典，而不是一个预先修整过的字典。

然而，也就是说，对于一次性解决，它真的很快。(Perl正则表达式是在C!:))

以下是一些不同的代码添加:

sub readDict_nofilter {
  my $fn = shift;
  my $re = shift;
  my $d  = Tree::Trie->new();

  # Dictionary Loading
  open my $fh, '<', $fn;
  while ( my $line = <$fh> ) {
      chomp($line);
      $d->add( uc($line) );
  }
  return $d;
}

sub benchmark_io { 
  use Benchmark qw( cmpthese :hireswallclock );
   # generate a random 16 character string 
   # to simulate there being an input grid. 
  my $regexen = sub { 
      my @letters = 'A' .. 'Z' ; 
      my @lo = ();
      for( 1..16 ){ 
          push @lo , $_ ; 
      }
      my $c  = join '', @lo;
      $c = "[^$c]";
      return qr/$c/i;
  };
  cmpthese( 200 , { 
      filtered => sub { 
          readDict('dict.txt', $regexen->() );
      }, 
      unfiltered => sub {
          readDict_nofilter('dict.txt');
      }
  });
}

           s/iter unfiltered   filtered
unfiltered   8.16         --       -94%
filtered    0.464      1658%         --

Ps: 8.16 * 200 = 27分钟。

对VB不感兴趣?:)我忍不住了。我解决这个问题的方法不同于这里提出的许多解决方案。

我的时间是:

将字典和单词前缀加载到哈希表:.5到1秒。 找单词:平均不到10毫秒。

编辑:web主机服务器上的字典加载时间比我的家用电脑长1到1.5秒。

我不知道随着服务器负载的增加，时间会恶化到什么程度。

我把我的解决方案写成了。net的网页。myvrad.com/boggle

我用的是原题中提到的字典。

字母在单词中不能重复使用。只找到3个字符或以上的单词。

我使用所有唯一的单词前缀和单词的哈希表，而不是一个trie。我不知道什么是trie，所以我学到了一些东西。除了完整的单词之外，创建单词前缀列表的想法最终使我的时间减少到一个可观的数字。

阅读代码注释以获得更多详细信息。

代码如下:

Imports System.Collections.Generic
Imports System.IO

Partial Class boggle_Default

    'Bob Archer, 4/15/2009

    'To avoid using a 2 dimensional array in VB I'm not using typical X,Y
    'coordinate iteration to find paths.
    '
    'I have locked the code into a 4 by 4 grid laid out like so:
    ' abcd
    ' efgh
    ' ijkl
    ' mnop
    ' 
    'To find paths the code starts with a letter from a to p then
    'explores the paths available around it. If a neighboring letter
    'already exists in the path then we don't go there.
    '
    'Neighboring letters (grid points) are hard coded into
    'a Generic.Dictionary below.



    'Paths is a list of only valid Paths found. 
    'If a word prefix or word is not found the path is not
    'added and extending that path is terminated.
    Dim Paths As New Generic.List(Of String)

    'NeighborsOf. The keys are the letters a to p.
    'The value is a string of letters representing neighboring letters.
    'The string of neighboring letters is split and iterated later.
    Dim NeigborsOf As New Generic.Dictionary(Of String, String)

    'BoggleLetters. The keys are mapped to the lettered grid of a to p.
    'The values are what the user inputs on the page.
    Dim BoggleLetters As New Generic.Dictionary(Of String, String)

    'Used to store last postition of path. This will be a letter
    'from a to p.
    Dim LastPositionOfPath As String = ""

    'I found a HashTable was by far faster than a Generic.Dictionary 
    ' - about 10 times faster. This stores prefixes of words and words.
    'I determined 792773 was the number of words and unique prefixes that
    'will be generated from the dictionary file. This is a max number and
    'the final hashtable will not have that many.
    Dim HashTableOfPrefixesAndWords As New Hashtable(792773)

    'Stores words that are found.
    Dim FoundWords As New Generic.List(Of String)

    'Just to validate what the user enters in the grid.
    Dim ErrorFoundWithSubmittedLetters As Boolean = False

    Public Sub BuildAndTestPathsAndFindWords(ByVal ThisPath As String)
        'Word is the word correlating to the ThisPath parameter.
        'This path would be a series of letters from a to p.
        Dim Word As String = ""

        'The path is iterated through and a word based on the actual
        'letters in the Boggle grid is assembled.
        For i As Integer = 0 To ThisPath.Length - 1
            Word += Me.BoggleLetters(ThisPath.Substring(i, 1))
        Next

        'If my hashtable of word prefixes and words doesn't contain this Word
        'Then this isn't a word and any further extension of ThisPath will not
        'yield any words either. So exit sub to terminate exploring this path.
        If Not HashTableOfPrefixesAndWords.ContainsKey(Word) Then Exit Sub

        'The value of my hashtable is a boolean representing if the key if a word (true) or
        'just a prefix (false). If true and at least 3 letters long then yay! word found.
        If HashTableOfPrefixesAndWords(Word) AndAlso Word.Length > 2 Then Me.FoundWords.Add(Word)

        'If my List of Paths doesn't contain ThisPath then add it.
        'Remember only valid paths will make it this far. Paths not found
        'in the HashTableOfPrefixesAndWords cause this sub to exit above.
        If Not Paths.Contains(ThisPath) Then Paths.Add(ThisPath)

        'Examine the last letter of ThisPath. We are looking to extend the path
        'to our neighboring letters if any are still available.
        LastPositionOfPath = ThisPath.Substring(ThisPath.Length - 1, 1)

        'Loop through my list of neighboring letters (representing grid points).
        For Each Neighbor As String In Me.NeigborsOf(LastPositionOfPath).ToCharArray()
            'If I find a neighboring grid point that I haven't already used
            'in ThisPath then extend ThisPath and feed the new path into
            'this recursive function. (see recursive.)
            If Not ThisPath.Contains(Neighbor) Then Me.BuildAndTestPathsAndFindWords(ThisPath & Neighbor)
        Next
    End Sub

    Protected Sub ButtonBoggle_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles ButtonBoggle.Click

        'User has entered the 16 letters and clicked the go button.

        'Set up my Generic.Dictionary of grid points, I'm using letters a to p -
        'not an x,y grid system.  The values are neighboring points.
        NeigborsOf.Add("a", "bfe")
        NeigborsOf.Add("b", "cgfea")
        NeigborsOf.Add("c", "dhgfb")
        NeigborsOf.Add("d", "hgc")
        NeigborsOf.Add("e", "abfji")
        NeigborsOf.Add("f", "abcgkjie")
        NeigborsOf.Add("g", "bcdhlkjf")
        NeigborsOf.Add("h", "cdlkg")
        NeigborsOf.Add("i", "efjnm")
        NeigborsOf.Add("j", "efgkonmi")
        NeigborsOf.Add("k", "fghlponj")
        NeigborsOf.Add("l", "ghpok")
        NeigborsOf.Add("m", "ijn")
        NeigborsOf.Add("n", "ijkom")
        NeigborsOf.Add("o", "jklpn")
        NeigborsOf.Add("p", "klo")

        'Retrieve letters the user entered.
        BoggleLetters.Add("a", Me.TextBox1.Text.ToLower.Trim())
        BoggleLetters.Add("b", Me.TextBox2.Text.ToLower.Trim())
        BoggleLetters.Add("c", Me.TextBox3.Text.ToLower.Trim())
        BoggleLetters.Add("d", Me.TextBox4.Text.ToLower.Trim())
        BoggleLetters.Add("e", Me.TextBox5.Text.ToLower.Trim())
        BoggleLetters.Add("f", Me.TextBox6.Text.ToLower.Trim())
        BoggleLetters.Add("g", Me.TextBox7.Text.ToLower.Trim())
        BoggleLetters.Add("h", Me.TextBox8.Text.ToLower.Trim())
        BoggleLetters.Add("i", Me.TextBox9.Text.ToLower.Trim())
        BoggleLetters.Add("j", Me.TextBox10.Text.ToLower.Trim())
        BoggleLetters.Add("k", Me.TextBox11.Text.ToLower.Trim())
        BoggleLetters.Add("l", Me.TextBox12.Text.ToLower.Trim())
        BoggleLetters.Add("m", Me.TextBox13.Text.ToLower.Trim())
        BoggleLetters.Add("n", Me.TextBox14.Text.ToLower.Trim())
        BoggleLetters.Add("o", Me.TextBox15.Text.ToLower.Trim())
        BoggleLetters.Add("p", Me.TextBox16.Text.ToLower.Trim())

        'Validate user entered something with a length of 1 for all 16 textboxes.
        For Each S As String In BoggleLetters.Keys
            If BoggleLetters(S).Length <> 1 Then
                ErrorFoundWithSubmittedLetters = True
                Exit For
            End If
        Next

        'If input is not valid then...
        If ErrorFoundWithSubmittedLetters Then
            'Present error message.
        Else
            'Else assume we have 16 letters to work with and start finding words.
            Dim SB As New StringBuilder

            Dim Time As String = String.Format("{0}:{1}:{2}:{3}", Date.Now.Hour.ToString(), Date.Now.Minute.ToString(), Date.Now.Second.ToString(), Date.Now.Millisecond.ToString())

            Dim NumOfLetters As Integer = 0
            Dim Word As String = ""
            Dim TempWord As String = ""
            Dim Letter As String = ""
            Dim fr As StreamReader = Nothing
            fr = New System.IO.StreamReader(HttpContext.Current.Request.MapPath("~/boggle/dic.txt"))

            'First fill my hashtable with word prefixes and words.
            'HashTable(PrefixOrWordString, BooleanTrueIfWordFalseIfPrefix)
            While fr.Peek <> -1
                Word = fr.ReadLine.Trim()
                TempWord = ""
                For i As Integer = 0 To Word.Length - 1
                    Letter = Word.Substring(i, 1)
                    'This optimization helped quite a bit. Words in the dictionary that begin
                    'with letters that the user did not enter in the grid shouldn't go in my hashtable.
                    '
                    'I realize most of the solutions went with a Trie. I'd never heard of that before,
                    'which is one of the neat things about SO, seeing how others approach challenges
                    'and learning some best practices.
                    '
                    'However, I didn't code a Trie in my solution. I just have a hashtable with 
                    'all words in the dicitonary file and all possible prefixes for those words.
                    'A Trie might be faster but I'm not coding it now. I'm getting good times with this.
                    If i = 0 AndAlso Not BoggleLetters.ContainsValue(Letter) Then Continue While
                    TempWord += Letter
                    If Not HashTableOfPrefixesAndWords.ContainsKey(TempWord) Then
                        HashTableOfPrefixesAndWords.Add(TempWord, TempWord = Word)
                    End If
                Next
            End While

            SB.Append("Number of Word Prefixes and Words in Hashtable: " & HashTableOfPrefixesAndWords.Count.ToString())
            SB.Append("<br />")

            SB.Append("Loading Dictionary: " & Time & " - " & String.Format("{0}:{1}:{2}:{3}", Date.Now.Hour.ToString(), Date.Now.Minute.ToString(), Date.Now.Second.ToString(), Date.Now.Millisecond.ToString()))
            SB.Append("<br />")

            Time = String.Format("{0}:{1}:{2}:{3}", Date.Now.Hour.ToString(), Date.Now.Minute.ToString(), Date.Now.Second.ToString(), Date.Now.Millisecond.ToString())

            'This starts a path at each point on the grid an builds a path until 
            'the string of letters correlating to the path is not found in the hashtable
            'of word prefixes and words.
            Me.BuildAndTestPathsAndFindWords("a")
            Me.BuildAndTestPathsAndFindWords("b")
            Me.BuildAndTestPathsAndFindWords("c")
            Me.BuildAndTestPathsAndFindWords("d")
            Me.BuildAndTestPathsAndFindWords("e")
            Me.BuildAndTestPathsAndFindWords("f")
            Me.BuildAndTestPathsAndFindWords("g")
            Me.BuildAndTestPathsAndFindWords("h")
            Me.BuildAndTestPathsAndFindWords("i")
            Me.BuildAndTestPathsAndFindWords("j")
            Me.BuildAndTestPathsAndFindWords("k")
            Me.BuildAndTestPathsAndFindWords("l")
            Me.BuildAndTestPathsAndFindWords("m")
            Me.BuildAndTestPathsAndFindWords("n")
            Me.BuildAndTestPathsAndFindWords("o")
            Me.BuildAndTestPathsAndFindWords("p")

            SB.Append("Finding Words: " & Time & " - " & String.Format("{0}:{1}:{2}:{3}", Date.Now.Hour.ToString(), Date.Now.Minute.ToString(), Date.Now.Second.ToString(), Date.Now.Millisecond.ToString()))
            SB.Append("<br />")

            SB.Append("Num of words found: " & FoundWords.Count.ToString())
            SB.Append("<br />")
            SB.Append("<br />")

            FoundWords.Sort()
            SB.Append(String.Join("<br />", FoundWords.ToArray()))

            'Output results.
            Me.LiteralBoggleResults.Text = SB.ToString()
            Me.PanelBoggleResults.Visible = True

        End If

    End Sub

End Class

我建议根据单词做一个字母树。这棵树将由字母结构组成，像这样:

letter: char
isWord: boolean

然后构建树，每个深度添加一个新字母。换句话说，第一层是字母表;然后从这些树中，会有另外26个条目，以此类推，直到你把所有的单词都拼出来。坚持这个解析树，它将使所有可能的答案更快地查找。

使用这个解析过的树，您可以非常快速地找到解决方案。下面是伪代码:

BEGIN: 
    For each letter:
        if the struct representing it on the current depth has isWord == true, enter it as an answer.
        Cycle through all its neighbors; if there is a child of the current node corresponding to the letter, recursively call BEGIN on it.

这可以通过一些动态编程来加快。例如，在你的样本中，两个“A”都在一个“E”和一个“W”旁边，这(从它们击中它们的点来看)是相同的。我没有足够的时间来详细说明这个代码，但我想你们可以理解。

此外，我相信你会找到其他解决方案，如果你谷歌“Boggle solver”。

    package ProblemSolving;

import java.util.HashSet;
import java.util.Set;

/**
 * Given a 2-dimensional array of characters and a
 * dictionary in which a word can be searched in O(1) time.
 * Need to print all the words from array which are present
 * in dictionary. Word can be formed in any direction but
 * has to end at any edge of array.
 * (Need not worry much about the dictionary)
 */
public class DictionaryWord {
    private static char[][] matrix = new char[][]{
            {'a', 'f', 'h', 'u', 'n'},
            {'e', 't', 'a', 'i', 'r'},
            {'a', 'e', 'g', 'g', 'o'},
            {'t', 'r', 'm', 'l', 'p'}
    };
    private static int dim_x = matrix.length;
    private static int dim_y = matrix[matrix.length -1].length;
    private static Set<String> wordSet = new HashSet<String>();

    public static void main(String[] args) {
        //dictionary
        wordSet.add("after");
        wordSet.add("hate");
        wordSet.add("hair");
        wordSet.add("air");
        wordSet.add("eat");
        wordSet.add("tea");

        for (int x = 0; x < dim_x; x++) {
            for (int y = 0; y < dim_y; y++) {
                checkAndPrint(matrix[x][y] + "");
                int[][] visitedMap = new int[dim_x][dim_y];
                visitedMap[x][y] = 1;
                recursion(matrix[x][y] + "", visitedMap, x, y);
            }
        }
    }

    private static void checkAndPrint(String word) {
        if (wordSet.contains(word)) {
            System.out.println(word);
        }
    }

    private static void recursion(String word, int[][] visitedMap, int x, int y) {
        for (int i = Math.max(x - 1, 0); i < Math.min(x + 2, dim_x); i++) {
            for (int j = Math.max(y - 1, 0); j < Math.min(y + 2, dim_y); j++) {
                if (visitedMap[i][j] == 1) {
                    continue;
                } else {
                    int[][] newVisitedMap = new int[dim_x][dim_y];
                    for (int p = 0; p < dim_x; p++) {
                        for (int q = 0; q < dim_y; q++) {
                           newVisitedMap[p][q] = visitedMap[p][q];
                        }
                    }
                    newVisitedMap[i][j] = 1;
                    checkAndPrint(word + matrix[i][j]);
                    recursion(word + matrix[i][j], newVisitedMap, i, j);
                }
            }
        }
    }

}