PHP greedy algorithm solves 0-1 knapsack problem case Analysis, 0-1 example Analysis _php tutorial

PHP greedy algorithm solves 0-1 knapsack problem case analysis, 0-1 instance analysis

This article describes the PHP greedy algorithm to solve the 0-1 knapsack problem method. Share to everyone for your reference. The specific analysis is as follows:

Greedy algorithm solves 0-1 knapsack problem, the global optimal solution is obtained by local optimal solution! More flexible than dynamic planning to solve knapsack problems!

0-1 knapsack greedy algorithm problem class tanxin{public $weight;  Public $price;    Public function __construct ($weight =0, $price =0) {$this->weight= $weight;  $this->price= $price;  }}//Generate Data $n=10;for ($i =1; $i <= $n; $i + +) {$weight =rand (1,20);  $price =rand (1,10); $x [$i]=new tanxin ($weight, $price);}  Output function display ($x) {$len =count ($x);    foreach ($x as $val) {echo $val->weight, ', $val->price; Echo '
';  }}//sort function Tsort (& $x) {$len =count ($x) by price and weight ratio;      for ($i =1; $i <= $len; $i + +) {for ($j =1; $j <= $len-$i; $j + +) {$temp = $x [$j];      $res = $x [$j +1]->price/$x [$j +1]->weight;      $temres = $temp->price/$temp->weight;        if ($res > $temres) {$x [$j]= $x [$j +1];      $x [$j +1]= $temp;  }}}}//greedy algorithm function tanxin ($x, $totalweight =50) {$len =count ($x);  $allprice = 0;    for ($i =1; $i <= $len; $i + +) {if ($x [$i]->weight> $totalweight) break;      else{$allprice + = $x [$i]->price;    $totalweight = $totalweight-$x [$i]->weight;  }} if ($i < $len) $allprice + = $x [$i]->price* ($totalweight/$x [$i]->weight); return $allprice;} Tsort ($x);//Sort display ($x) in a non-ascending order;//display echo ' 0-1 knapsack optimal solution: '; echo tanxin ($x);

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