/*** js數(shù)組實現(xiàn)權(quán)重概率分配* @param  Array  arr    js數(shù)組，參數(shù)類型[Object,Object,Object……]* @return  Array        返回一個隨機(jī)元素，概率為其percent/所有percent之和，參數(shù)類型Object* @author  shuiguang*/function weight_rand(arr){  //參數(shù)arr元素必須含有percent屬性，參考如下所示  /*  var arr = [{      name : '1',      percent : 1    }, {      name : '2',      percent : 2    }, {      name : '3',      percent : 1    }, {      name : '4',      percent : 2    }  ];  */  var total = 0;  var i, j, percent;  //下標(biāo)標(biāo)記數(shù)組，按照上面的例子，單倍情況下其組成為[1,2,2,3,4,4]  var index = new Array();  for (i = 0; i < arr.length; i++) {    //判斷元素的權(quán)重，為了實現(xiàn)小數(shù)權(quán)重，先將所有的值放大100倍    percent = 'undefined' != typeof(arr[i].percent) ? parseInt(arr[i].percent*100) : 0;    for (j = 0; j < percent; j++) {      index.push(i);    }    total += percent;  }  //隨機(jī)數(shù)值，其值介于0-5的整數(shù)  var rand = Math.floor(Math.random() * total);  return arr[index[rand]];}

/*** js數(shù)組實現(xiàn)權(quán)重概率分配，支持?jǐn)?shù)字比模式(支持2位小數(shù))和百分比模式(不支持小數(shù)，最后一個元素多退少補(bǔ))* @param  Array  arr  js數(shù)組，參數(shù)類型[Object,Object,Object……]* @return  Array      返回一個隨機(jī)元素，概率為其weight/所有weight之和，參數(shù)類型Object* @author  shuiguang*/function weight_rand(arr){	//參數(shù)arr元素必須含有weight屬性，參考如下所示	//var arr=[{name:'1',weight:1.5},{name:'2',weight:2.5},{name:'3',weight:3.5}];	//var arr=[{name:'1',weight:'15%'},{name:'2',weight:'25%'},{name:'3',weight:'35%'}];	//求出最大公約數(shù)以計算縮小倍數(shù)，perMode為百分比模式	var per;	var maxNum = 0;	var perMode = false;	//自定義Math求最小公約數(shù)方法	Math.gcd = function(a,b){		var min = Math.min(a,b);		var max = Math.max(a,b);		var result = 1;		if(a === 0 || b===0){			return max;		}		for(var i=min; i>=1; i--){			if(min % i === 0 && max % i === 0){				result = i;				break;			}		}		return result;	};		//使用clone元素對象拷貝仍然會造成浪費，但是使用權(quán)重數(shù)組對應(yīng)關(guān)系更省內(nèi)存	var weight_arr = new Array();	for (i = 0; i < arr.length; i++) {		if('undefined' != typeof(arr[i].weight))		{			if(arr[i].weight.toString().indexOf('%') !== -1) {				per = Math.floor(arr[i].weight.toString().replace('%',''));				perMode = true;			}else{				per = Math.floor(arr[i].weight*100);			}		}else{			per = 0;		}		weight_arr[i] = per;		maxNum = Math.gcd(maxNum, per);	}	//數(shù)字比模式，3:5:7，其組成[0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2]	//百分比模式，元素所占百分比為15%，25%，35%	var index = new Array();	var total = 0;	var len = 0;	if(perMode){		for (i = 0; i < arr.length; i++) {			//len表示存儲arr下標(biāo)的數(shù)據(jù)塊長度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長度			len = weight_arr[i];			for (j = 0; j < len; j++){				//超過100%跳出，后面的舍棄				if(total >= 100){					break;				}				index.push(i);				total++;			}		}		//使用最后一個元素補(bǔ)齊100%		while(total < 100){			index.push(arr.length-1);			total++;		}	}else{		for (i = 0; i < arr.length; i++) {			//len表示存儲arr下標(biāo)的數(shù)據(jù)塊長度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長度			len = weight_arr[i]/maxNum;			for (j = 0; j < len; j++){				index.push(i);			}			total += len;		}	}	//隨機(jī)數(shù)值，其值為0-11的整數(shù)，數(shù)據(jù)塊根據(jù)權(quán)重分塊	var rand = Math.floor(Math.random()*total);	//console.log(index);	return arr[index[rand]];}var arr=[{name:'1',weight:1.5},{name:'2',weight:2.5},{name:'3',weight:3.5}];console.log(weight_rand(arr));var arr=[{name:'1',weight:'15%'},{name:'2',weight:'25%'},{name:'3',weight:'35%'}];console.log(weight_rand(arr));var prize_arr = [	{'id':1, 'prize':'平板電腦', 'weight':1},	{'id':2, 'prize':'數(shù)碼相機(jī)', 'weight':2},	{'id':3, 'prize':'音箱設(shè)備', 'weight':10},	{'id':4, 'prize':'4G優(yōu)盤', 'weight':12},	{'id':5, 'prize':'10Q幣', 'weight':22},	{'id':6, 'prize':'下次沒準(zhǔn)就能中哦', 'weight':50}    ];var times = 100000;var prize;var pingban = 0;var shuma = 0;var yinxiang = 0;var youpan = 0;var qb = 0;var xc = 0;var start = new Date().getTime();for($i=0; $i<times; $i++){	prize = weight_rand(prize_arr);	if(prize.prize == '平板電腦')	{		pingban++;	}else if(prize.prize == '數(shù)碼相機(jī)'){		shuma++;	}else if(prize.prize == '音箱設(shè)備'){		yinxiang++;	}else if(prize.prize == '4G優(yōu)盤'){		youpan++;	}else if(prize.prize == '10Q幣'){		qb++;	}else if(prize.prize == '下次沒準(zhǔn)就能中哦'){		xc++;	}}var stop = new Date().getTime();console.log('平板電腦：'+pingban/times+', 數(shù)碼相機(jī)：'+shuma/times+', 音箱設(shè)備：'+yinxiang/times+', 4G優(yōu)盤：'+youpan/times+', 10Q幣：'+qb/times+', 下次沒準(zhǔn)就能中哦：'+xc/times);console.log('耗費時間：'+(stop-start)/1000+'秒');

/*** php數(shù)組實現(xiàn)權(quán)重概率分配，支持?jǐn)?shù)字比模式(支持2位小數(shù))和百分比模式(不支持小數(shù)，最后一個元素多退少補(bǔ))* @param  array  $arr  php數(shù)組，參數(shù)類型array(array(),array(),array()……)* @return  array      返回一個隨機(jī)元素，概率為其percent/所有percent之和，參數(shù)類型array()* @author  shuiguang*/function weight_rand($arr){  //參數(shù)arr元素必須含有percent屬性，參考如下所示  //$arr=array(array('name'=>'1','weight'=>1.5),array('name'=>'2','weight'=>1.5),array('name'=>'3','weight'=>1.5));  //$arr=array(array('name'=>'1','weight'=>'15%'),array('name'=>'2','weight'=>'25%'),array('name'=>'3','weight'=>'35%'));  //求出最大公約數(shù)以計算縮小倍數(shù)，perMode為百分比模式  $perMode = false;  $maxNum = 0;  //自定義求最小公約數(shù)方法  $gcd = function($a, $b)  {    $min = min($a, $b);    $max = max($a, $b);    $result = 1;    if($a === 0 || $b === 0)    {      return $max;    }    for($i=$min; $i>=1; $i--)    {      if($min % $i === 0 && $max % $i === 0)      {        $result = $i;        break;      }    }    return $result;  };  //使用傳地址可能會影響后面的結(jié)果，但是使用權(quán)重數(shù)組對應(yīng)關(guān)系更省內(nèi)存  $weight_arr = array();  $arr_len = count($arr);  for($i=0; $i<$arr_len; $i++)  {    if(isset($arr[$i]['weight']))    {      if(strpos($arr[$i]['weight'], '%') !== false)      {        $per = floor(str_replace('%', '', $arr[$i]['weight']));        $perMode = true;      }else{        $per = floor($arr[$i]['weight']*100);      }    }else{      $per = 0;    }    $weight_arr[$i] = $per;    $maxNum = call_user_func($gcd, $maxNum, $per);  }  //數(shù)字比模式，3:5:7，其組成[0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2]  //百分比模式，元素所占百分比為15%，25%，35%  $index = array();  $total = 0;  if($perMode)  {    for($i=0; $i<$arr_len; $i++)    {      //$len表示存儲$arr下標(biāo)的數(shù)據(jù)塊長度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長度      $len = $weight_arr[$i];      for ($j = 0; $j < $len; $j++)      {        //超過100%跳出，后面的舍棄        if($total >= 100)        {          break;        }        $index[] = $i;        $total++;      }    }    //使用最后一個元素補(bǔ)齊100%    while($total < 100)    {      $index[] = $arr_len-1;      $total++;    }  }else{    for($i=0; $i<$arr_len; $i++)    {      //len表示存儲arr下標(biāo)的數(shù)據(jù)塊長度，已優(yōu)化至最小整數(shù)形式減小索引數(shù)組的長度      $len = $weight_arr[$i]/$maxNum;      for ($j = 0; $j < $len; $j++)      {        $index[] = $i;      }      $total += $len;    }  }  //隨機(jī)數(shù)值，其值為0-11的整數(shù)，數(shù)據(jù)塊根據(jù)權(quán)重分塊  $rand = floor(mt_rand(0, $total));	//修復(fù)php隨機(jī)函數(shù)可以取臨界值造成的bug  $rand = $rand == $total ? $total-1 : $rand;  return $arr[$index[$rand]];}$arr=array(array('name'=>'1','weight'=>1.5),array('name'=>'2','weight'=>1.5),array('name'=>'3','weight'=>1.5));p(weight_rand($arr));$arr=array(array('name'=>'1','weight'=>'15%'),array('name'=>'2','weight'=>'25%'),array('name'=>'3','weight'=>'35%'));p(weight_rand($arr));$prize_arr = array(	'0' => array('id'=>1, 'prize'=>'平板電腦', 'weight'=>1),	'1' => array('id'=>2, 'prize'=>'數(shù)碼相機(jī)', 'weight'=>5),	'2' => array('id'=>3, 'prize'=>'音箱設(shè)備', 'weight'=>10),	'3' => array('id'=>4, 'prize'=>'4G優(yōu)盤', 'weight'=>12),	'4' => array('id'=>5, 'prize'=>'10Q幣', 'weight'=>22),	'5' => array('id'=>6, 'prize'=>'下次沒準(zhǔn)就能中哦', 'weight'=>50),);$start = time();$result = array();$times = 100000;for($i=0; $i<$times; $i++){	$row = weight_rand($prize_arr);	if(array_key_exists($row['prize'], $result))	{		$result[$row['prize']] ++;	}else{		$result[$row['prize']] = 1;	}}$cost = time() - $start;p($result);p('耗費時間：'.$cost.'秒');function p($var){  echo "<pre>";  if($var === false)  {    echo 'false';  }else if($var === ''){    print_r("''");  }else{    print_r($var);  }  echo "</pre>";}