PHP Backtracking method solves 0-1 knapsack problem case analysis, 0-1 instance Analysis _php Tutorial

PHP Backtracking method solves 0-1 knapsack problem case analysis, 0-1 instance analysis

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

This code is written according to the pseudo code of the software designer tutorial;
The most troublesome is not to change the pseudo-code to PHP, but the array subscript starting from 0, and the corresponding subscript judgment problem;
With a debug output piece written on

<?php $v _arr = Array (11,21,31,33,43,53,55,65);  $w _arr = Array (1,11,21,23,33,43,45,55);  $n = count ($w _arr);  Test output Var_dump (BKNAP1);//var_dump (bound (139,89,7,110));    function bound ($v, $w, $k, $W _total) {global $v _arr, $w _arr, $n;    $b = $v;    $c = $w;//var_dump ($W _total); Var_dump ($n); Var_dump ($k); Var_dump ($v); Var_dump ($w);//die;      for ($i = $k +1; $i < $n; $i + +) {$c = $c + $w _arr[$i];      Var_dump ($W _total); Var_dump ($c);      if ($c < $W _total) $b + = $v _arr[$i];        Else{//var_dump (($c-$W _total)/$w _arr[$i]) * $v _arr[$i]);        $b = $b + (n ($c-$W _total)/$w _arr[$i]) * $v _arr[$i];       return $b;    }}/*var_dump ('------bound head ');    Var_dump ($K);    Var_dump ($b);   Var_dump ('------bound end '); */return $b;    } function Bknap1 ($W _total) {global $v _arr, $w _arr, $n;    $CW = $CP = 0;    $k = 0;    $fp =-1;        while (true) {while ($k < $n && $CW + $w _arr[$k]<= $W _total) {$CW + = $w _arr[$k];        $CP + = $v _arr[$k]; $Y _arr[$k] = 1;      $k +=1;      }//var_dump ($CW), Var_dump ($CP), Var_dump ($Y _arr), Var_dump ($k); Var_dump ($n);        if ($k = = $n) {$fp = $CP;        $FW = $CW;        $k = $n-1; $X _arr = $Y _arr;//bound ($CP, $CW, $k, $W _total),//var_dump (Bound ($CP, $CW, $k, $W _total), $fp, $k);d ie;//var_dump ($FP);      Var_dump ($FW); Var_dump ($Y _arr); Var_dump ($k); Var_dump ($n);      }else{$Y _arr[$k] = 0;      }//var_dump ($Y _arr); Var_dump ($k); Var_dump ($n)//die;//var_dump (bound ($CP, $CW, $k, $W _total), $fp);d ie;        while (Bound ($CP, $CW, $k, $W _total) <= $fp) {while ($k >=0 && $Y _arr[$k]!=1) {$k-= 1;        } if ($k <0) {return $X _arr;        } var_dump ($k);        $Y _arr[$k] = 0;        $CW-= $w _arr[$k];      $CP-= $v _arr[$k];    } $k + = 1; }}?>

I hope this article is helpful to everyone's PHP programming.

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