Spiral matrix traversal PHP

[betazold]

<?php
 
$r1 = rand(0, 7);
$r2 = rand(0, 7);
$a = [];
for ($i = 0; $i < $r1; $i++) {
 for ($j = 0; $j < $r2; $j++) {
   $a[$i][$j] = rand(1, 10);
}
}
$r = [];
for ($i = 0; $i < $r1; $i++) {
$t = [];
 for ($j = 0; $j < $r2; $j++) {
  $t[] = $a[$i][$j];
}
$r[] = '[' . implode(', ', $t) . ']';
}
 
echo "[\n" . implode(",\n", $r) . "\n];\n\n";
 
//var_dump([$r1, $r2]);
/**$a = [
[6, 10, 9],
[3, 5, 2],
[8, 2, 5],
[4, 1, 8],
[6, 10, 5],
[6, 8, 10]
];
*/
 
/**
$a = [
 [1, 2, 3,    4],
 [14, 15, 16, 5],
 [13, 20, 17, 6],
 [12, 19, 18, 7],
 [11, 10, 9,  8]
];*/
 
$rows = sizeof($a);
if ($rows) {
$cols = sizeof($a[0]);
} else {
 $cols = 0; 
}
 
$total = $rows * $cols;
 
$i = $cols;
$d = 'cols';
$j = 0;
$c = 0;
$x = 0;
$y = 0;
 
$dy = 0;
$dx = 1;
 
 
$r = [];
while ($c < $total) {
  $r[] = $a[$y][$x];
  $j++;
  if ($j === $i) {
    $j = 0;
    list($dx, $dy) = [-$dy, $dx];
    if ($d === 'cols') {
       $rows--;
       $i = $rows;
       $d = 'rows';
    } else {
       $cols--;
       $i = $cols;
       $d = 'cols';
    }
  }
  $x = $x + $dx; $y = $y + $dy;
 
  $c++;
}
 
if (empty($r)) echo "Empty result\n";
echo implode(' ', $r);

@темы: PHP