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)


当前回答

我也用Java解决了这个问题。我的实现有269行,非常容易使用。首先,您需要创建Boggler类的一个新实例,然后用网格作为参数调用solve函数。在我的电脑上加载5万个单词的字典大约需要100毫秒,它在大约10-20毫秒内找到单词。找到的单词存储在一个数组列表中,即foundWords。

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;

public class Boggler {
    private ArrayList<String> words = new ArrayList<String>();      
    private ArrayList<String> roundWords = new ArrayList<String>(); 
    private ArrayList<Word> foundWords = new ArrayList<Word>();     
    private char[][] letterGrid = new char[4][4];                   
    private String letters;                                         

    public Boggler() throws FileNotFoundException, IOException, URISyntaxException {
        long startTime = System.currentTimeMillis();

        URL path = GUI.class.getResource("words.txt");
        BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(new File(path.toURI()).getAbsolutePath()), "iso-8859-1"));
        String line;
        while((line = br.readLine()) != null) {
            if(line.length() < 3 || line.length() > 10) {
                continue;
            }

            this.words.add(line);
        }
    }

    public ArrayList<Word> getWords() {
        return this.foundWords;
    }

    public void solve(String letters) {
        this.letters = "";
        this.foundWords = new ArrayList<Word>();

        for(int i = 0; i < letters.length(); i++) {
            if(!this.letters.contains(letters.substring(i, i + 1))) {
                this.letters += letters.substring(i, i + 1);
            }
        }

        for(int i = 0; i < 4; i++) {
            for(int j = 0; j < 4; j++) {
                this.letterGrid[i][j] = letters.charAt(i * 4 + j);
            }
        }

        System.out.println(Arrays.deepToString(this.letterGrid));               

        this.roundWords = new ArrayList<String>();      
        String pattern = "[" + this.letters + "]+";     

        for(int i = 0; i < this.words.size(); i++) {

            if(this.words.get(i).matches(pattern)) {
                this.roundWords.add(this.words.get(i));
            }
        }

        for(int i = 0; i < this.roundWords.size(); i++) {
            Word word = checkForWord(this.roundWords.get(i));

            if(word != null) {
                System.out.println(word);
                this.foundWords.add(word);
            }
        }       
    }

    private Word checkForWord(String word) {
        char initial = word.charAt(0);
        ArrayList<LetterCoord> startPoints = new ArrayList<LetterCoord>();

        int x = 0;  
        int y = 0;
        for(char[] row: this.letterGrid) {
            x = 0;

            for(char letter: row) {
                if(initial == letter) {
                    startPoints.add(new LetterCoord(x, y));
                }

                x++;
            }

            y++;
        }

        ArrayList<LetterCoord> letterCoords = null;
        for(int initialTry = 0; initialTry < startPoints.size(); initialTry++) {
            letterCoords = new ArrayList<LetterCoord>();    

            x = startPoints.get(initialTry).getX(); 
            y = startPoints.get(initialTry).getY();

            LetterCoord initialCoord = new LetterCoord(x, y);
            letterCoords.add(initialCoord);

            letterLoop: for(int letterIndex = 1; letterIndex < word.length(); letterIndex++) {
                LetterCoord lastCoord = letterCoords.get(letterCoords.size() - 1);  
                char currentChar = word.charAt(letterIndex);                        

                ArrayList<LetterCoord> letterLocations = getNeighbours(currentChar, lastCoord.getX(), lastCoord.getY());

                if(letterLocations == null) {
                    return null;    
                }       

                for(int foundIndex = 0; foundIndex < letterLocations.size(); foundIndex++) {
                    if(letterIndex != word.length() - 1 && true == false) {
                        char nextChar = word.charAt(letterIndex + 1);
                        int lastX = letterCoords.get(letterCoords.size() - 1).getX();
                        int lastY = letterCoords.get(letterCoords.size() - 1).getY();

                        ArrayList<LetterCoord> possibleIndex = getNeighbours(nextChar, lastX, lastY);
                        if(possibleIndex != null) {
                            if(!letterCoords.contains(letterLocations.get(foundIndex))) {
                                letterCoords.add(letterLocations.get(foundIndex));
                            }
                            continue letterLoop;
                        } else {
                            return null;
                        }
                    } else {
                        if(!letterCoords.contains(letterLocations.get(foundIndex))) {
                            letterCoords.add(letterLocations.get(foundIndex));

                            continue letterLoop;
                        }
                    }
                }
            }

            if(letterCoords != null) {
                if(letterCoords.size() == word.length()) {
                    Word w = new Word(word);
                    w.addList(letterCoords);
                    return w;
                } else {
                    return null;
                }
            }
        }

        if(letterCoords != null) {
            Word foundWord = new Word(word);
            foundWord.addList(letterCoords);

            return foundWord;
        }

        return null;
    }

    public ArrayList<LetterCoord> getNeighbours(char letterToSearch, int x, int y) {
        ArrayList<LetterCoord> neighbours = new ArrayList<LetterCoord>();

        for(int _y = y - 1; _y <= y + 1; _y++) {
            for(int _x = x - 1; _x <= x + 1; _x++) {
                if(_x < 0 || _y < 0 || (_x == x && _y == y) || _y > 3 || _x > 3) {
                    continue;
                }

                if(this.letterGrid[_y][_x] == letterToSearch && !neighbours.contains(new LetterCoord(_x, _y))) {
                    neighbours.add(new LetterCoord(_x, _y));
                }
            }
        }

        if(neighbours.isEmpty()) {
            return null;
        } else {
            return neighbours;
        }
    }
}

class Word {
    private String word;    
    private ArrayList<LetterCoord> letterCoords = new ArrayList<LetterCoord>();

    public Word(String word) {
        this.word = word;
    }

    public boolean addCoords(int x, int y) {
        LetterCoord lc = new LetterCoord(x, y);

        if(!this.letterCoords.contains(lc)) {
            this.letterCoords.add(lc);

            return true;
        }

        return false;
    }

    public void addList(ArrayList<LetterCoord> letterCoords) {
        this.letterCoords = letterCoords;
    } 

    @Override
    public String toString() {
        String outputString = this.word + " ";
        for(int i = 0; i < letterCoords.size(); i++) {
            outputString += "(" + letterCoords.get(i).getX() + ", " + letterCoords.get(i).getY() + ") ";
        }

        return outputString;
    }

    public String getWord() {
        return this.word;
    }

    public ArrayList<LetterCoord> getList() {
        return this.letterCoords;
    }
}

class LetterCoord extends ArrayList {
    private int x;          
    private int y;          

    public LetterCoord(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public int getX() {
        return this.x;
    }

    public int getY() {
        return this.y;
    }

    @Override
    public boolean equals(Object o) {
        if(!(o instanceof LetterCoord)) {
            return false;
        }

        LetterCoord lc = (LetterCoord) o;

        if(this.x == lc.getX() &&
                this.y == lc.getY()) {
            return true;
        }

        return false;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 29 * hash + this.x;
        hash = 24 * hash + this.y;
        return hash;
    }
}

其他回答

我用c语言解决了这个问题。在我的机器上运行大约需要48毫秒(其中98%的时间花在从磁盘加载字典和创建trie上)。字典是/usr/share/dict/american-english,有62886个单词。

源代码

我知道我已经非常晚了,但是我之前用PHP做了一个——只是为了好玩……

http://www.lostsockdesign.com.au/sandbox/boggle/index.php?letters=fxieamloewbxastu 在0.90108秒内找到75个单词(133分)

F……X . .我 .............. E ............... 一个 ...................................... 米 .............................. L ............................ O ............................... E .................... W ............................ B .......................... X 一个 .................. 年代 .................................................. T ................. U…

给出了一些程序实际在做什么的指示-每个字母是它开始查看模式的地方,而每个'。这显示了中国试图走的一条道路。越多越好。“它搜索得越远。

如果你想要密码,请告诉我…这是一个可怕的PHP和HTML的混合体,从来没有想过要看到阳光,所以我不敢在这里张贴:P

下面是使用NLTK工具包中的预定义单词的解决方案 NLTK有NLTK。语料库包,我们有一个叫做单词的包,它包含超过20万个英语单词,你可以简单地把它们都用到你的程序中。

一旦创建你的矩阵转换成一个字符数组,并执行这段代码

import nltk
from nltk.corpus import words
from collections import Counter

def possibleWords(input, charSet):
    for word in input:
        dict = Counter(word)
        flag = 1
        for key in dict.keys():
            if key not in charSet:
                flag = 0
        if flag == 1 and len(word)>5: #its depends if you want only length more than 5 use this otherwise remove that one. 
            print(word)


nltk.download('words')
word_list = words.words()
# prints 236736
print(len(word_list))
charSet = ['h', 'e', 'l', 'o', 'n', 'v', 't']
possibleWords(word_list, charSet)

输出:

eleven
eleventh
elevon
entente
entone
ethene
ethenol
evolve
evolvent
hellhole
helvell
hooven
letten
looten
nettle
nonene
nonent
nonlevel
notelet
novelet
novelette
novene
teenet
teethe
teevee
telethon
tellee
tenent
tentlet
theelol
toetoe
tonlet
toothlet
tootle
tottle
vellon
velvet
velveteen
venene
vennel
venthole
voeten
volent
volvelle
volvent
voteen

我希望你能得到它。

最快的解决方案可能是将字典存储在一个trie中。然后,创建一个三元组队列(x, y, s),其中队列中的每个元素对应于一个可以在网格中拼写的单词的前缀s,结束于位置(x, y)。初始化队列中有N x N个元素(其中N是网格的大小),网格中的每个正方形都有一个元素。然后,算法进行如下:

While the queue is not empty:
  Dequeue a triple (x, y, s)
  For each square (x', y') with letter c adjacent to (x, y):
    If s+c is a word, output s+c
    If s+c is a prefix of a word, insert (x', y', s+c) into the queue

如果将字典存储在trie中,则可以在常数时间内测试s+c是否是单词或单词的前缀(前提是还在每个队列数据中保留一些额外的元数据,例如指向trie中当前节点的指针),因此此算法的运行时间为O(可拼写的单词数量)。

[编辑]下面是我刚刚编写的Python实现:

#!/usr/bin/python

class TrieNode:
    def __init__(self, parent, value):
        self.parent = parent
        self.children = [None] * 26
        self.isWord = False
        if parent is not None:
            parent.children[ord(value) - 97] = self

def MakeTrie(dictfile):
    dict = open(dictfile)
    root = TrieNode(None, '')
    for word in dict:
        curNode = root
        for letter in word.lower():
            if 97 <= ord(letter) < 123:
                nextNode = curNode.children[ord(letter) - 97]
                if nextNode is None:
                    nextNode = TrieNode(curNode, letter)
                curNode = nextNode
        curNode.isWord = True
    return root

def BoggleWords(grid, dict):
    rows = len(grid)
    cols = len(grid[0])
    queue = []
    words = []
    for y in range(cols):
        for x in range(rows):
            c = grid[y][x]
            node = dict.children[ord(c) - 97]
            if node is not None:
                queue.append((x, y, c, node))
    while queue:
        x, y, s, node = queue[0]
        del queue[0]
        for dx, dy in ((1, 0), (1, -1), (0, -1), (-1, -1), (-1, 0), (-1, 1), (0, 1), (1, 1)):
            x2, y2 = x + dx, y + dy
            if 0 <= x2 < cols and 0 <= y2 < rows:
                s2 = s + grid[y2][x2]
                node2 = node.children[ord(grid[y2][x2]) - 97]
                if node2 is not None:
                    if node2.isWord:
                        words.append(s2)
                    queue.append((x2, y2, s2, node2))

    return words

使用示例:

d = MakeTrie('/usr/share/dict/words')
print(BoggleWords(['fxie','amlo','ewbx','astu'], d))

输出:

['fa', 'xi', 'ie', 'io', 'el', 'am', 'ax', 'ae', 'aw', 'mi', 'ma', 'me', 'lo', 'li', 'oe', 'ox', 'em', 'ea', 'ea', 'es', 'wa', 'we', 'wa', 'bo', 'bu', 'as', 'aw', 'ae', 'st', 'se', 'sa', 'tu', 'ut', 'fam', 'fae', 'imi', 'eli', 'elm', 'elb', 'ami', 'ama', 'ame', 'aes', 'awl', 'awa', 'awe', 'awa', 'mix', 'mim', 'mil', 'mam', 'max', 'mae', 'maw', 'mew', 'mem', 'mes', 'lob', 'lox', 'lei', 'leo', 'lie', 'lim', 'oil', 'olm', 'ewe', 'eme', 'wax', 'waf', 'wae', 'waw', 'wem', 'wea', 'wea', 'was', 'waw', 'wae', 'bob', 'blo', 'bub', 'but', 'ast', 'ase', 'asa', 'awl', 'awa', 'awe', 'awa', 'aes', 'swa', 'swa', 'sew', 'sea', 'sea', 'saw', 'tux', 'tub', 'tut', 'twa', 'twa', 'tst', 'utu', 'fama', 'fame', 'ixil', 'imam', 'amli', 'amil', 'ambo', 'axil', 'axle', 'mimi', 'mima', 'mime', 'milo', 'mile', 'mewl', 'mese', 'mesa', 'lolo', 'lobo', 'lima', 'lime', 'limb', 'lile', 'oime', 'oleo', 'olio', 'oboe', 'obol', 'emim', 'emil', 'east', 'ease', 'wame', 'wawa', 'wawa', 'weam', 'west', 'wese', 'wast', 'wase', 'wawa', 'wawa', 'boil', 'bolo', 'bole', 'bobo', 'blob', 'bleo', 'bubo', 'asem', 'stub', 'stut', 'swam', 'semi', 'seme', 'seam', 'seax', 'sasa', 'sawt', 'tutu', 'tuts', 'twae', 'twas', 'twae', 'ilima', 'amble', 'axile', 'awest', 'mamie', 'mambo', 'maxim', 'mease', 'mesem', 'limax', 'limes', 'limbo', 'limbu', 'obole', 'emesa', 'embox', 'awest', 'swami', 'famble', 'mimble', 'maxima', 'embolo', 'embole', 'wamble', 'semese', 'semble', 'sawbwa', 'sawbwa']

Notes: This program doesn't output 1-letter words, or filter by word length at all. That's easy to add but not really relevant to the problem. It also outputs some words multiple times if they can be spelled in multiple ways. If a given word can be spelled in many different ways (worst case: every letter in the grid is the same (e.g. 'A') and a word like 'aaaaaaaaaa' is in your dictionary), then the running time will get horribly exponential. Filtering out duplicates and sorting is trivial to due after the algorithm has finished.

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。