Online PHP editor | output for T6Nvb

<?php function gdr_encode($val) { // all characters that json encode without escaping $chrs = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 !#$%&\'()*+,-.:;<=>?@[]^_`{|}~'; $base = strlen($chrs); $str = ''; while ($val > 0) { $str = $chrs[$val % $base] . $str; $val = (int)($val / $base); } return $str; } function gdr_decode($str) { // all characters that json encode without escaping $chrs = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789 !#$%&\'()*+,-.:;<=>?@[]^_`{|}~'; $base = strlen($chrs); $map = array(); for ($i=0; $i<$base; $i++) { $map[$chrs[$i]] = $i; } $val = 0; for ($i=0; $i<strlen($str); $i++) { $val *= $base; $val += (int)$map[$str[$i]]; } return $val; } function duration($val) { if ($val < 24) { return sprintf('%d', $val).'h'; } if ($val < 24*10) { return sprintf('%1.1f', $val/24).'d'; } if ($val < 168*10) { return sprintf('%1.1f', $val/168).'w'; } //if ($val < 730*10) { // return sprintf('%1.1f', $val/730).'m'; //} return sprintf('%1.1f', $val/8760).'y'; } function search($min, $max, $k){ if ($max < $min) { return null; } $mid = round(($min+$max)/2, 0)-1; $len = strlen(gdr_encode($mid)); if ($len == $k && strlen(gdr_encode($mid+1)) == $k+1) { return $mid; } if ($len < $k) { return search($min, $mid-1, $k); } return search($mid+1, $max, $k); } function insert(&$vals, $n) { $min = intval('1'.str_repeat('0', $n-1)); $max = intval(str_repeat('9', $n)); $vals[] = $min; $vals[] = $max; $len = strlen(gdr_encode($min)); if ($len == strlen(gdr_encode($max))) { return; } $mid = search($min, $max, $len); if ($mid === null) { return; } $vals[] = $mid; $vals[] = $mid+1; } $vals = array(0); for ($i=1; $i<8; $i++) { insert($vals, $i); } $vals = array_unique($vals); sort($vals); //$vals = array( // 0, 1, 99, 100, 255, 256, 999, 1000, 9999, 10000, 65535, 65536, 99999, // 100000, 250000, 500000, 750000, 999999, 1000000, 9999999, //4294967295, 4294967296 //); echo sprintf("%7s %7s %7s %4s\n", 'num', 'str', 'time', 'cmp'); foreach ($vals as $val) { $enc = gdr_encode($val); $dec = gdr_decode($enc); if ($dec !== $val) { echo "ERROR: $val => $enc => $dec\n"; } else { echo sprintf("%7d %7s %7s %4d\n", $dec, "\"$enc\"", duration($val), strlen($enc)+2-strlen($val)); } }