Bridge the problem, ask for the shortest time

Xiao Ming a 5 people in a bridge at night, Xiao Ming Bridge to 1 minutes, Xiao Ming's brother Bridge to 3 minutes, Xiao Ming's father Bridge to 6 minutes, Xiao Ming's mother bridge to 8 minutes, Xiao Ming's grandfather Bridge to 12 minutes; This bridge can only be 2 people, because it is the night, bridge must carry the lamp, Xiaoming has a lamp, Lit after 30 minutes will be extinguished, ask how to arrange, to ensure that Xiao Ming's family before the lights go off the bridge.

Wrote a PHP program to solve this kind of problem. There are questions, welcome to point out.

<?PHP/*Bridge Problem*/main ();functionMain () {$arr=Array(3,1,12,8,6); PrintBridge$arr);}functionBridge$arr){    $route=""; if(Count($arr) ==1){        $route.=$arr[0]; }     ElseIf(Count($arr) ==2){        $route.=$arr[0]>$arr[1]?$arr[0]:$arr[1]; }Else{        Sort($arr); $route.=$arr[1]. " = "; $route.=$arr[0]. " = "; $ARRTMP=$arr; unset($ARRTMP[0]); unset($ARRTMP[1]); Sort($ARRTMP);  while(Count($ARRTMP) >1){            //Key            if($ARRTMP[Count($ARRTMP) -2]+$arr[0]>2*$arr[1]){                $route.=$ARRTMP[Count($ARRTMP)-1]. " = "; $route.=$arr[1]. " = "; $route.=$arr[1]. " = "; $route.=$arr[0]. " = "; }Else{                $route.=$ARRTMP[Count($ARRTMP)-1]. " = "; $route.=$arr[0]. " = "; $route.=$ARRTMP[Count($ARRTMP)-2]. " = "; $route.=$arr[0]. " = "; }            unset($ARRTMP[Count($ARRTMP)-2]); unset($ARRTMP[Count($ARRTMP)]); }        if(Count($ARRTMP) ==1){            $route.=$ARRTMP[Count($ARRTMP)-1]; }Else{            $route=substr($route, 0,strlen($route)-strlen("= =".)$arr[0]. " = ")); }        return $route; }}

Bridge the problem, ask for the shortest time