Month: August 2016

擬似乱数

<html><body style="font-size:32px; line-height:32px;">
<?php
// set color
    $colors = array("red", "blue", "yellow", "green", "black");
// draw 16x16
    for ($i = 0; $i < 256; $i++){
        $r = rand(0, count($colors)-1);
        $c = $colors&#91;$r&#93;;
        echo "<span style='color:$c'>■</span>";
        if ($i % 16 == 15) echo "<br>";
    }
?></body></html>

usortで安定ソート

$data = [
    ['name'=>'Arai', 'score'=>30],
    ['name'=>'Inoue', 'score'=>40],
    ['name'=>'Utada', 'score'=>30],
    ['name'=>'Okuda', 'score'=>40],
    ['name'=>'Kato', 'score'=>23]
    ];

    // record
    for ($i = 0; $i < count($data); i++){
        $data[$i]["id"] = $i + 1;
    }
    usort($data, function($a, $b){
          if ($a['score'] == $b['score']){
          return ($a['id'] > $b['id']) ? 1 : -1;
          });
    foreach ($data as $u){
    echo $u['id'].":".$u['name'].":".$u['score']."\n";
    }

usort()関数

// setting data
$arr = [
    ['name']=>'Kan', 'point'=>4],
    ['name']=>'Kenji', 'point'=>5],
    ['name']=>'Akai', 'point'=>3],
    ['name']=>'Genta', 'point'=>4],
    ['name']=>'Shizuka', 'point'=>8],
    ];
    $point_cmp = function ($a, $b) {
        return ($a['point'] < $b['point']) ? -1 : 1;
    };

    usort($arr, $point_cmp);
    //result
    foreach ($arr as $u) {
    echo $u['name'].":".$u['point']."\n";
    }

クイックソート


// quick sort
    function quick_sort(&$arr){
        if (count($arr) < 2) return $arr;
        $left = $right = array();
        $pivot = array_shift($arr);
        foreach ($arr as $v) {
            if ($v < $pivot){
                $left[] = $v;
            } else {
                right[] = $v;
            }
        }
        quick_sort($left);
        quick_sort($right);
        $arr = array_merge($left, array($pivot), $right);
    }


    $arr = array(1,100,24,40,12,4);
    quick_sort($arr);
    echo implode(', ', $arr)."\n";

コムソート

 1 || $swap){
                if ($gap > 1) {
                    $gap = floor($gap / 1.25);
                    if ($gap == 9 || $gap == 10) $gap = 11;
                }
                $swap = false;
                $i = 0;
                while($i + $gap < size) {
                    if ($arr[$i] > $arr[$i + $gap]){
                        $tmp = $arr[$i];
                        $arr[$i] = $arr[$i + $gap];
                        $arr[$i + $gap] = $tmp;
                        $swap = true;
                    }
                    $i++;
                }
                
            }
        }
    }
    $arr = array(100, 3, 30, 20, 44, 32);
    comb_sort($arr);
    echo implode(", ", $arr)."\n"