<?php
if (phpversion() < '5.2.1') { die('php sucks'); }
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('%1.2f', $val/24).'d';
}
if ($val < 168*10) {
return sprintf('%1.2f', $val/168).'w';
}
//if ($val < 730*10) {
// return sprintf('%1.2f', $val/730).'m';
//}
return sprintf('%1.2f', $val/8760).'y';
}
function cmp($val) {
return strlen(gdr_encode($val))+2-strlen($val);
}
function insert(&$vals, $n) {
$min = intval('1'.str_repeat('0', $n-1));
$max = intval(str_repeat('9', $n));
$vals[] = $min;
$vals[] = $max;
$cmp_min = cmp($min);
$cmp_max = cmp($max);
if ($cmp_min === $cmp_max) {
return;
}
// binary search for edges
if ($cmp_min+1 !== $cmp_max) {
echo "ERROR: invalid search assumption: possibly missing edges: [$min => $cmp_min, $max => $cmp_max]\n";
}
while ($min <= $max) {
$mid = (int)(($min+$max)/2);
$cmp_mid = cmp($mid);
//echo "trace: [$min => $cmp_min, $mid => $cmp_mid, $max=>$cmp_max]\n";
if ($cmp_min === $cmp_mid && $cmp_mid !== cmp($mid+1)) {
$vals[] = $mid;
$vals[] = $mid+1;
return;
}
//$vals[] = $mid; // include visited values in results
if ($min === $max) {
return;
}
if ($cmp_min < $cmp_mid) {
$max = $mid-1;
} else {
$min = $mid+1;
}
}
}
$vals = array(0);
for ($i=1; $i<8; $i++) {
insert($vals, $i);
}
$vals = array_unique($vals);
sort($vals);
echo sprintf("%7s %7s %8s %4s\n", 'num', 'str', 'time', 'cmp');
foreach ($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 %8s %4d\n", $dec, "\"$enc\"", duration($val), cmp($val));
}
}
preferences:
24.81 ms | 402 KiB | 5 Q