Task: Word search



C#: using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Wordseach
{
    static class Program
    {
        readonly static int[,] dirs = {{1, 0}, {0, 1}, {1, 1}, {1, -1}, {-1, 0},
            {0, -1}, {-1, -1}, {-1, 1}};

        class Grid
        {
            public char[,] Cells = new char[nRows, nCols];
            public List<string> Solutions = new List<string>();
            public int NumAttempts;
        }

        readonly static int nRows = 10;
        readonly static int nCols = 10;
        readonly static int gridSize = nRows * nCols;
        readonly static int minWords = 25;

        readonly static Random rand = new Random();

        static void Main(string[] args)
        {
            PrintResult(CreateWordSearch(ReadWords("unixdict.txt")));
        }

        private static List<string> ReadWords(string filename)
        {
            int maxLen = Math.Max(nRows, nCols);

            return System.IO.File.ReadAllLines(filename)
                .Select(s => s.Trim().ToLower())
                .Where(s => Regex.IsMatch(s, "^[a-z]{3," + maxLen + "}$"))
                .ToList();
        }

        private static Grid CreateWordSearch(List<string> words)
        {
            int numAttempts = 0;

            while (++numAttempts < 100)
            {
                words.Shuffle();

                var grid = new Grid();
                int messageLen = PlaceMessage(grid, "Rosetta Code");
                int target = gridSize - messageLen;

                int cellsFilled = 0;
                foreach (var word in words)
                {
                    cellsFilled += TryPlaceWord(grid, word);
                    if (cellsFilled == target)
                    {
                        if (grid.Solutions.Count >= minWords)
                        {
                            grid.NumAttempts = numAttempts;
                            return grid;
                        }
                        else break; 
                    }
                }
            }
            return null;
        }

        private static int TryPlaceWord(Grid grid, string word)
        {
            int randDir = rand.Next(dirs.GetLength(0));
            int randPos = rand.Next(gridSize);

            for (int dir = 0; dir < dirs.GetLength(0); dir++)
            {
                dir = (dir + randDir) % dirs.GetLength(0);

                for (int pos = 0; pos < gridSize; pos++)
                {
                    pos = (pos + randPos) % gridSize;

                    int lettersPlaced = TryLocation(grid, word, dir, pos);
                    if (lettersPlaced > 0)
                        return lettersPlaced;
                }
            }
            return 0;
        }

        private static int TryLocation(Grid grid, string word, int dir, int pos)
        {
            int r = pos / nCols;
            int c = pos % nCols;
            int len = word.Length;

            
            if ((dirs[dir, 0] == 1 && (len + c) > nCols)
                    || (dirs[dir, 0] == -1 && (len - 1) > c)
                    || (dirs[dir, 1] == 1 && (len + r) > nRows)
                    || (dirs[dir, 1] == -1 && (len - 1) > r))
                return 0;

            int rr, cc, i, overlaps = 0;

            
            for (i = 0, rr = r, cc = c; i < len; i++)
            {
                if (grid.Cells[rr, cc] != 0 && grid.Cells[rr, cc] != word[i])
                {
                    return 0;
                }

                cc += dirs[dir, 0];
                rr += dirs[dir, 1];
            }

            
            for (i = 0, rr = r, cc = c; i < len; i++)
            {
                if (grid.Cells[rr, cc] == word[i])
                    overlaps++;
                else
                    grid.Cells[rr, cc] = word[i];

                if (i < len - 1)
                {
                    cc += dirs[dir, 0];
                    rr += dirs[dir, 1];
                }
            }

            int lettersPlaced = len - overlaps;
            if (lettersPlaced > 0)
            {
                grid.Solutions.Add($"{word,-10} ({c},{r})({cc},{rr})");
            }

            return lettersPlaced;
        }

        private static int PlaceMessage(Grid grid, string msg)
        {
            msg = Regex.Replace(msg.ToUpper(), "[^A-Z]", "");

            int messageLen = msg.Length;
            if (messageLen > 0 && messageLen < gridSize)
            {
                int gapSize = gridSize / messageLen;

                for (int i = 0; i < messageLen; i++)
                {
                    int pos = i * gapSize + rand.Next(gapSize);
                    grid.Cells[pos / nCols, pos % nCols] = msg[i];
                }
                return messageLen;
            }
            return 0;
        }

        public static void Shuffle<T>(this IList<T> list)
        {
            int n = list.Count;
            while (n > 1)
            {
                n--;
                int k = rand.Next(n + 1);
                T value = list[k];
                list[k] = list[n];
                list[n] = value;
            }
        }

        private static void PrintResult(Grid grid)
        {
            if (grid == null || grid.NumAttempts == 0)
            {
                Console.WriteLine("No grid to display");
                return;
            }
            int size = grid.Solutions.Count;

            Console.WriteLine("Attempts: " + grid.NumAttempts);
            Console.WriteLine("Number of words: " + size);

            Console.WriteLine("\n     0  1  2  3  4  5  6  7  8  9");
            for (int r = 0; r < nRows; r++)
            {
                Console.Write("\n{0}   ", r);
                for (int c = 0; c < nCols; c++)
                    Console.Write(" {0} ", grid.Cells[r, c]);
            }

            Console.WriteLine("\n");

            for (int i = 0; i < size - 1; i += 2)
            {
                Console.WriteLine("{0}   {1}", grid.Solutions[i],
                        grid.Solutions[i + 1]);
            }
            if (size % 2 == 1)
                Console.WriteLine(grid.Solutions[size - 1]);

            Console.ReadLine();
        }        
    }
}


Go: package main

import (
    "bufio"
    "fmt"
    "log"
    "math/rand"
    "os"
    "regexp"
    "strings"
    "time"
)

var dirs = [][]int{{1, 0}, {0, 1}, {1, 1}, {1, -1}, {-1, 0}, {0, -1}, {-1, -1}, {-1, 1}}

const (
    nRows    = 10
    nCols    = nRows
    gridSize = nRows * nCols
    minWords = 25
)

var (
    re1 = regexp.MustCompile(fmt.Sprintf("^[a-z]{3,%d}$", nRows))
    re2 = regexp.MustCompile("[^A-Z]")
)

type grid struct {
    numAttempts int
    cells       [nRows][nCols]byte
    solutions   []string
}

func check(err error) {
    if err != nil {
        log.Fatal(err)
    }
}

func readWords(fileName string) []string {
    file, err := os.Open(fileName)
    check(err)
    defer file.Close()
    var words []string
    scanner := bufio.NewScanner(file)
    for scanner.Scan() {
        word := strings.ToLower(strings.TrimSpace(scanner.Text()))
        if re1.MatchString(word) {
            words = append(words, word)
        }
    }
    check(scanner.Err())
    return words
}

func createWordSearch(words []string) *grid {
    var gr *grid
outer:
    for i := 1; i < 100; i++ {
        gr = new(grid)
        messageLen := gr.placeMessage("Rosetta Code")
        target := gridSize - messageLen
        cellsFilled := 0
        rand.Shuffle(len(words), func(i, j int) {
            words[i], words[j] = words[j], words[i]
        })
        for _, word := range words {
            cellsFilled += gr.tryPlaceWord(word)
            if cellsFilled == target {
                if len(gr.solutions) >= minWords {
                    gr.numAttempts = i
                    break outer
                } else { 
                    break
                }
            }
        }
    }
    return gr
}

func (gr *grid) placeMessage(msg string) int {
    msg = strings.ToUpper(msg)
    msg = re2.ReplaceAllLiteralString(msg, "")
    messageLen := len(msg)
    if messageLen > 0 && messageLen < gridSize {
        gapSize := gridSize / messageLen
        for i := 0; i < messageLen; i++ {
            pos := i*gapSize + rand.Intn(gapSize)
            gr.cells[pos/nCols][pos%nCols] = msg[i]
        }
        return messageLen
    }
    return 0
}

func (gr *grid) tryPlaceWord(word string) int {
    randDir := rand.Intn(len(dirs))
    randPos := rand.Intn(gridSize)
    for dir := 0; dir < len(dirs); dir++ {
        dir = (dir + randDir) % len(dirs)
        for pos := 0; pos < gridSize; pos++ {
            pos = (pos + randPos) % gridSize
            lettersPlaced := gr.tryLocation(word, dir, pos)
            if lettersPlaced > 0 {
                return lettersPlaced
            }
        }
    }
    return 0
}

func (gr *grid) tryLocation(word string, dir, pos int) int {
    r := pos / nCols
    c := pos % nCols
    le := len(word)

    
    if (dirs[dir][0] == 1 && (le+c) > nCols) ||
        (dirs[dir][0] == -1 && (le-1) > c) ||
        (dirs[dir][1] == 1 && (le+r) > nRows) ||
        (dirs[dir][1] == -1 && (le-1) > r) {
        return 0
    }
    overlaps := 0

    
    rr := r
    cc := c
    for i := 0; i < le; i++ {
        if gr.cells[rr][cc] != 0 && gr.cells[rr][cc] != word[i] {
            return 0
        }
        cc += dirs[dir][0]
        rr += dirs[dir][1]
    }

    
    rr = r
    cc = c
    for i := 0; i < le; i++ {
        if gr.cells[rr][cc] == word[i] {
            overlaps++
        } else {
            gr.cells[rr][cc] = word[i]
        }
        if i < le-1 {
            cc += dirs[dir][0]
            rr += dirs[dir][1]
        }
    }

    lettersPlaced := le - overlaps
    if lettersPlaced > 0 {
        sol := fmt.Sprintf("%-10s (%d,%d)(%d,%d)", word, c, r, cc, rr)
        gr.solutions = append(gr.solutions, sol)
    }
    return lettersPlaced
}

func printResult(gr *grid) {
    if gr.numAttempts == 0 {
        fmt.Println("No grid to display")
        return
    }
    size := len(gr.solutions)
    fmt.Println("Attempts:", gr.numAttempts)
    fmt.Println("Number of words:", size)
    fmt.Println("\n     0  1  2  3  4  5  6  7  8  9")
    for r := 0; r < nRows; r++ {
        fmt.Printf("\n%d   ", r)
        for c := 0; c < nCols; c++ {
            fmt.Printf(" %c ", gr.cells[r][c])
        }
    }
    fmt.Println("\n")
    for i := 0; i < size-1; i += 2 {
        fmt.Printf("%s   %s\n", gr.solutions[i], gr.solutions[i+1])
    }
    if size%2 == 1 {
        fmt.Println(gr.solutions[size-1])
    }
}

func main() {
    rand.Seed(time.Now().UnixNano())
    unixDictPath := "/usr/share/dict/words"
    printResult(createWordSearch(readWords(unixDictPath)))
}