PHP tree deep calendar generation maze and A* automatic pathfinding algorithm example analysis

Analysis of examples of deep programming maze generation for PHP trees and A* automatic pathfinding algorithm

This article mainly introduces the deep programming maze generation and A* automatic pathfinding for PHP trees. Pathfinding algorithm, an example analysis of the techniques of implementing A* pathfinding algorithm in PHP, which has certain reference value. Friends who need it can refer to it

The example in this article describes the deep calendar generation maze of PHP tree and the A* automatic pathfinding algorithm. Share it with everyone for your reference. The specific analysis is as follows:

A colleague recommended Sansi’s maze algorithm. After reading it, I thought it was pretty good, so I converted it to PHP
Sansi's maze algorithm uses the principle of tree depth traversal. The maze generated in this way is quite thin, and the number of dead ends is relatively small!
There is only one path between any two points.

As for the A* pathfinding algorithm, it is the most popular fully automatic pathfinding algorithm

No further nonsense, just paste the code

Maze generation class:

The code is as follows:

class Maze{
// Maze Create
private $_w;
private $_h;
private $_grids;
private $_walkHistory;
private $_walkHistory2;
private $_targetSteps;
// Construct
public function Maze() {
$this->_w = 6;
$this->_h = 6;
$this->_grids = array();
}
// 设置迷宫大小
public function set($width = 6, $height = 6) {
if ( $width > 0 ) $this->_w = $width;
if ( $height > 0 ) $this->_h = $height;
return $this;
}
// 取到迷宫
public function get() {
return $this->_grids;
}
// 生成迷宫
public function create() {
$this->_init();
return $this->_walk(rand(0, count($this->_grids) -1 ));
}
// 获取死胡同点
public function block($n = 0, $rand = false) {
$l = count($this->_grids);
for( $i = 1; $i < $l; $i++ ) {
$v = $this->_grids[$i];
if ( $v == 1 || $v == 2 || $v == 4 || $v == 8 ) {
$return[] = $i;
}
}
// 随机取点
if ( $rand ) shuffle($return);

if ( $n == 0 ) return $return;

if ( $n == 1 ) {
return array_pop($return);
} else {
return array_slice($return, 0, $n);
}
}
/**
|------------------------------------------------- ---------------
| Series of functions to generate maze
|------------------------------------------------- ---------------
*/
private function _walk($startPos) {
$this->_walkHistory = array();
$this->_walkHistory2 = array();
$curPos = $startPos;
while ($this->_getNext0() != -1) {
$curPos = $this->_step($curPos);
if ( $curPos === false ) break;
}
return $this;
}
private function _getTargetSteps($curPos) {
$p = 0;
$a = array();
$p = $curPos - $this->_w;
if ($p > 0 && $this->_grids[$p] === 0 && ! $this->_isRepeating($p)) {
array_push($a, $p);
} else {
array_push($a, -1);
}
$p = $curPos + 1;
if ($p % $this->_w != 0 && $this->_grids[$p] === 0 && ! $this->_isRepeating($p)) {
array_push($a, $p);
} else {
array_push($a, -1);
}
$p = $curPos + $this->_w;
if ($p < count($this->_grids) && $this->_grids[$p] === 0 && ! $this->_isRepeating($p)) {
array_push($a, $p);
} else {
array_push($a, -1);
}
$p = $curPos - 1;
if (($curPos % $this->_w) != 0 && $this->_grids[$p] === 0 && ! $this->_isRepeating($p)) {
array_push($a, $p);
} else {
array_push($a, -1);
}
return $a;
}
private function _noStep() {
$l = count($this->_targetSteps);
for ($i = 0; $i < $l; $i ++) {
if ($this->_targetSteps[$i] != -1) return false;
}
return true;
}
private function _step($curPos) {
$this->_targetSteps = $this->_getTargetSteps($curPos);
if ( $this->_noStep() ) {
if ( count($this->_walkHistory) > 0 ) {
$tmp = array_pop($this->_walkHistory);
} else {
return false;
}
array_push($this->_walkHistory2, $tmp);
return $this->_step($tmp);
}
$r = rand(0, 3);
while ( $this->_targetSteps[$r] == -1) {
$r = rand(0, 3);
}
$nextPos = $this->_targetSteps[$r];
$isCross = false;
if ( $this->_grids[$nextPos] != 0)
$isCross = true;
if ($r == 0) {
$this->_grids[$curPos] ^= 1;
$this->_grids[$nextPos] ^= 4;
} elseif ($r == 1) {
$this->_grids[$curPos] ^= 2;
$this->_grids[$nextPos] ^= 8;
} elseif ($r == 2) {
$this->_grids[$curPos] ^= 4;
$this->_grids[$nextPos] ^= 1;
} elseif ($r == 3) {
$this->_grids[$curPos] ^= 8;
$this->_grids[$nextPos] ^= 2;
}
array_push($this->_walkHistory, $curPos);
return $isCross ? false : $nextPos;
}
private function _isRepeating($p) {
$l = count($this->_walkHistory);
for ($i = 0; $i < $l; $i ++) {
if ($this->_walkHistory[$i] == $p) return true;
}
$l = count($this->_walkHistory2);
for ($i = 0; $i < $l; $i ++) {
if ($this->_walkHistory2[$i] == $p) return true;
}
return false;
}
private function _getNext0() {
$l = count($this->_grids);

for ($i = 0; $i <= $l; $i++ ) {
if ( $this->_grids[$i] == 0) return $i;
}
return -1;
}
private function _init() {
$this->_grids = array();
for ($y = 0; $y < $this->_h; $y ++) {
for ($x = 0; $x < $this->_w; $x ++) {
array_push($this->_grids, 0);
}
}
return $this;
}
}

A*寻路算法

代码如下:

class AStar{
// A-star
private $_open;
private $_closed;
private $_start;
private $_end;
private $_grids;
private $_w;
private $_h;
// Construct
public function AStar(){
$this->_w = null;
$this->_h = null;
$this->_grids = null;
}
public function set($width, $height, $grids) {
$this->_w = $width;
$this->_h = $height;
$this->_grids = $grids;
return $this;
}
// 迷宫中寻路
public function search($start = false, $end = false) {
return $this->_search($start, $end);
}
/**
|------------------------------------------------- ---------------
| Automatic path finding - A-star algorithm
|------------------------------------------------- ---------------
*/
public function _search($start = false, $end = false) {
if ( $start !== false ) $this->_start = $start;
if ( $end !== false ) $this->_end = $end;
$_sh = $this->_getH($start);
$point['i'] = $start;
$point['f'] = $_sh;
$point['g'] = 0;
$point['h'] = $_sh;
$point['p'] = null;
$this->_open[] = $point;
$this->_closed[$start] = $point;
while ( 0 < count($this->_open) ) {
$minf = false;
foreach( $this->_open as $key => $maxNode ) {
if ( $minf === false || $minf > $maxNode['f'] ) {
$minIndex = $key;
}
}
$nowNode = $this->_open[$minIndex];
unset($this->_open[$minIndex]);
if ( $nowNode['i'] == $this->_end ) {
$tp = array();
while( $nowNode['p'] !== null ) {
array_unshift($tp, $nowNode['p']);
$nowNode = $this->_closed[$nowNode['p']];
}
array_push($tp, $this->_end);
break;
}
$this->_setPoint($nowNode['i']);
}
$this->_closed = array();
$this->_open = array();
return $tp;
}
private function _setPoint($me) {
$point = $this->_grids[$me];
// 所有可选方向入队列
if ( $point & 1 ) {
$next = $me - $this->_w;
$this->_checkPoint($me, $next);
}
if ( $point & 2 ) {
$next = $me + 1;
$this->_checkPoint($me, $next);
}
if ( $point & 4 ) {
$next = $me + $this->_w;
$this->_checkPoint($me, $next);
}
if ( $point & 8 ) {
$next = $me - 1;
$this->_checkPoint($me, $next);
}
}
private function _checkPoint($pNode, $next) {
if ( $this->_closed[$next] ) {
$_g = $this->_closed[$pNode]['g'] + $this->_getG($next);
if ( $_g < $check['g'] ) {
$this->_closed[$next]['g'] = $_g;
$this->_closed[$next]['f'] = $this->_closed[$next]['g'] + $this->_closed[$next]['h'];
$this->_closed[$next]['p'] = $pNode;
}
} else {
$point['p'] = $pNode;
$point['h'] = $this->_getH($next);
$point['g'] = $this->_getG($next);
$point['f'] = $point['h'] + $point['g'];
$point['i'] = $next;
$this->_open[] = $point;
$this->_closed[$next] = $point;
}
}
private function _getG($point) {
return abs($this->_start - $point);
}
private function _getH($point) {
return abs($this->_end - $point);
}
}

完整实例代码点击此处本站下载。

有需要大家可以直接下demo，看看效果！

希望本文所述对大家的php程序设计有所帮助。