地图几个相邻节点求出 $start 到 $end 的最短路径【算法】

2024年6月9日 82次阅读

方法一：(找到最短路径就跳出有限制不推荐)

<?PHP

$maps = [
            // 点    // 相邻节点列表
            1001 => [1002,1003,1005,1008,1009],
            1002 => [1001,1008],
            1003 => [1001,1005,1009],
            1005 => [1001,1003,1004,1009],
            1008 => [1001,1002,1009],
            1009 => [1001,1003,1004,1005,1007,1008],
            1004 => [1005,1009],
            1007 => [1009]
        ];

$obj = new parse($maps);
$obj->find('1002', '1007');
echo $obj->getBest();

class parse{

    var $data = array();
    var $used = array();
    var $chain = array();

    function parse($data){
        $this->data = $data;
    }
    /**
     * $start 开始节点
     * $end   结束节点
     * $chain 当前查找路线的经过节点
     */
    function find($start, $end, $chain=array()){
        //将起始节点加入当前朋友链中
        $chain[] = $start;
        //判断当前起点是否有朋友
        if(!isset($this->data[$start]))
            return;
        //判断当前的起点是否认识终点
        if(in_array($end, $this->data[$start])){
            $chain[] = $end;
            $this->chain = $chain;
            return ;
        }
        //如果当前"未完成路径" 比 "目前的最优路径" 长, 停止当前循环
        if(sizeof($chain)>=sizeof($this->chain) && sizeof($this->chain)!=0)
            return;
        //继续递归循环
        foreach($this->data[$start] as $value)
            if(!in_array($value, $chain))
                $this->find($value, $end, $chain);
    }

    function getBest(){
        $str = implode('->', $this->chain);
        return $str==null? "can't relation": $str;
    }
}
?>

方法二:(找到所有路径，自己选择推荐)

<?PHP

$maps = [
            // 点    // 相邻节点列表
            1001 => [1002,1003,1005,1008,1009],
            1002 => [1001,1008],
            1003 => [1001,1005,1009],
            1005 => [1001,1003,1004,1009],
            1008 => [1001,1002,1009],
            1009 => [1001,1003,1004,1005,1007,1008],
            1004 => [1005,1009],
            1007 => [1009]
        ];

$obj = new parse($maps);
$obj->find(1002, 1007);

class parse{

    var $data = array();

    function parse($data){
        $this->data = $data;
    }
    /**
     * $start 开始节点
     * $end   结束节点
     * $chain 当前查找路线的经过节点
     */
    function find($start, $end, $chain=array()){
        //将起始节点加入当前节点链中
        $chain[] = $start;
        //判断当前起点是否有相邻节点
        if(!isset($this->data[$start]))
            return;
        //判断当前的起点是否是终点的相邻节点
        if(in_array($end, $this->data[$start])){
            echo implode('->', $chain)."->$end".'<br/>';
            return ;
        }
        //继续递归循环
        foreach($this->data[$start] as $value)
            if(!in_array($value, $chain))
                $this->find($value, $end, $chain);
    }
}
?>

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