RabbitFarm

2021-08-22

Count Numbers / MineSweeper game: The Weekly Challenge 126

The examples used here are from The Weekly Challenge problem statement and demonstrate the working solution.

Part 1

You are given a positive integer $N. Write a script to print count of numbers from 1 to $N that don’t contain digit 1.

Solution


use strict;
use warnings;
sub has_1{
    my($x) = @_;
    return 1 if $x =~ tr/1//d > 0;
    return 0;   
}

sub count_with_1{
    my($n) = @_;
    my $x = 1;  
    my $count = 0; 
    {
        $count += has_1($x); 
        $x += 1;
        redo if $x <= $n; 
    }
    return $count; 
}

sub count_without_1{
    my($n) = @_;
    return $n - count_with_1($n);  
}

MAIN:{
    my $N;
    $N = 15;
    print count_without_1($N) . "\n"; 
    $N = 25;
    print count_without_1($N) . "\n"; 
}  

Sample Run


$ perl perl/ch-1.pl
8
13

Notes

Given the flexibility and richness of Perl there were many choices of how to determine the presence of a '1'. I decided to use tr which will helpfully return the number of changes made. In this case, what is returned is the number of 1's deleted. If this number is greater than zero then we know a 1 was found.

Part 2

You are given a rectangle with points marked with either x or *. Please consider the x as a land mine. Write a script to print a rectangle with numbers and x as in the Minesweeper game.

Solution


use strict;
use warnings;
sub initialize_grid{
    my($m, $n) = @_;
    my @grid; 
    for my $i (0 .. $m - 1){
        for my $j (0 .. $n - 1){
            $grid[$i][$j] = "*";   
            $grid[$i][$j] = "x" if rand() <= (1 / 3);   
        }  
    }  
    return @grid; 
}

sub make_grid{
    my($m, $n) = @_;
    my @initial_grid = initialize_grid($m, $n);  
    my @grid = map {[@$_]} @initial_grid; 
    for my $i (0 .. $m - 1){ 
        for my $j (0 .. $n - 1){
            unless($grid[$i][$j] eq "x"){
                my $mine_count = 0;
                $mine_count++ if $i >= 1 && $j >= 1 && $grid[$i - 1][$j - 1] eq "x"; 
                $mine_count++ if $i >= 1 && $grid[$i - 1][$j] eq "x"; 
                $mine_count++ if $i >=1 && $j < $n - 1 && $grid[$i - 1][$j + 1] eq "x"; 
                $mine_count++ if $j >= 1 && $grid[$i][$j - 1] eq "x"; 
                $mine_count++ if $j < $n - 1 && $grid[$i][$j + 1] eq "x"; 
                $mine_count++ if $i < $m - 1 && $j >= 1 && $grid[$i + 1][$j - 1] eq "x"; 
                $mine_count++ if $i < $m - 1 && $grid[$i + 1][$j] eq "x" ; 
                $mine_count++ if $i < $m - 1 && $j < $n - 1 && $grid[$i + 1][$j + 1] eq "x"; 
                $grid[$i][$j] = $mine_count; 
            } 
        }  
    } 
    return (\@initial_grid, \@grid); 
}  

sub print_grid{
    my @grid = @_; 
    for my $row (@grid){
        print "\t" . join(" ", @{$row}) . "\n"  
    } 
} 

MAIN:{
    my($m, $n) = @ARGV;
    my($initial_grid, $grid) = make_grid($m, $n);  
    print "Input:\n"; 
    print_grid(@{$initial_grid});      
    print "Output:\n"; 
    print_grid(@{$grid});      
}

Sample Run


$ perl perl/ch-2.pl 5 10
Input:
        x x * * * * x * * x
        * * x * x x x * x *
        * * * * * * * * * *
        x * x x * * * * * x
        * * x * x * * * x *
Output:
        x x 2 2 2 4 x 3 2 x
        2 3 x 2 x x x 3 x 2
        1 3 3 4 3 3 2 2 2 2
        x 3 x x 2 1 0 1 2 x
        1 3 x 4 x 1 0 1 x 2

Notes

References

Challenge 126

C++ solution for Part 1

C++ solution for Part 2

History of Minesweeper

posted at: 17:39 by: Adam Russell | path: /perl | permanent link to this entry