php回溯法解决0-1背包问题

<?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 );

//测试输出
var_dump(bknap1(110));

//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((1-($c-$W_total)/$w_arr[$i])*$v_arr[$i]);
$b = $b+(1-($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);die;
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,$k);die;
//var_dump($fp);var_dump($fw);var_dump($Y_arr);var_dump($k);var_dump($n);die;
}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);die;
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;
}
}

?>