一、冒泡排序

冒泡排序

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function bubbleSort(arr) {
    var len = arr.length;
    for(var i = 0; i < len - 1; i++) {
        for(var j = 0; j < len - 1 - i; j++) {
            if(arr[j] > arr[j+1]) {       // 相邻元素两两对比
                var temp = arr[j+1];       // 元素交换
                arr[j+1] = arr[j];
                arr[j] = temp;
            }
        }
    }
    return arr;
}

二、快速排序

快速排序

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function quickSort(arr, left, right) {
    var len = arr.length,
        partitionIndex,
        left = typeof(left) !='number' ? 0 : left,
        right = typeof(right) !='number' ? len - 1 : right;
 
    if(left < right) {
        partitionIndex = partition(arr, left, right);
        quickSort(arr, left, partitionIndex-1);
        quickSort(arr, partitionIndex+1, right);
    }
    return arr;
}
 
function partition(arr, left ,right) {    // 分区操作
    var pivot = left,                     // 设定基准值（pivot）
        index = pivot + 1;
    for(var i = index; i <= right; i++) {
        if(arr[i] < arr[pivot]) {
            swap(arr, i, index);
            index++;
        }       
    }
    swap(arr, pivot, index - 1);
    return index-1;
}
 
function swap(arr, i, j) {
    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
}

三、24点算法

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<?PHP
 
class TwentyFourCal {
    public  $needle = 24;
    public  $precision = '1e-6';
  
    function TwentyFourCal() {
    }
     
    private function notice($mesg) {
        var_dump($mesg);
    }
  
    /**
     * 取得用户输入方法
     */
    public function calculate($operants = array()) {
        try {
            $this->search($operants,4);
        } catch (Exception $e) {
            $this->notice($e->getMessage());
            return;
        }
        $this->notice('can\'t compute!');
        return;
    }
  
    /**
     * 求24点算法PHP实现
     */
    private function search($expressions,$level) {
        if ($level == 1) {
            $result = 'return ' . $expressions[0] . ';';
            if ( abs(eval($result) - $this->needle) <= $this->precision) {
                throw new Exception($expressions[0]);
            }
        }
        for ($i=0;$i<$level;$i++) {
            for ($j=$i+1;$j<$level;$j++) {
                $expLeft  = $expressions[$i];
                $expRight = $expressions[$j];
                $expressions[$j] = $expressions[$level - 1];
  
                $expressions[$i] = '(' . $expLeft . ' + ' . $expRight . ')';
                $this->search($expressions,$level - 1);
  
                $expressions[$i] = '(' . $expLeft . ' * ' . $expRight . ')';
                $this->search($expressions,$level - 1);
  
                $expressions[$i] = '(' . $expLeft . ' - ' . $expRight . ')';
                $this->search($expressions,$level - 1);
  
                $expressions[$i] = '(' . $expRight . ' - ' . $expLeft . ')';
                $this->search($expressions,$level - 1);
                 
                if ($expLeft != 0) {
                    $expressions[$i] = '(' . $expRight . ' / ' . $expLeft . ')';
                    $this->search($expressions,$level - 1);
                }
                 
                if ($expRight != 0) {
                    $expressions[$i] = '(' . $expLeft . ' / ' . $expRight . ')';
                    $this->search($expressions,$level - 1);
                }
                $expressions[$i] = $expLeft;
                $expressions[$j] = $expRight;
            }
        }
        return false;
    }
  
    function __destruct() {
    }
}