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Add solution 95.

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src/Algorithms/0095.unique-binary-search-trees-ii
- unique-binary-search-trees-ii.php

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	`1`	`+/**`
	`2`	`+ * Definition for a binary tree node.`
	`3`	`+ * class TreeNode {`
	`4`	`+ * public $val = null;`
	`5`	`+ * public $left = null;`
	`6`	`+ * public $right = null;`
	`7`	`+ * function __construct($value) { $this->val = $value; }`
	`8`	`+ * }`
	`9`	`+ */`
	`10`	`+class Solution {`
	`11`	`+`
	`12`	`+ /**`
	`13`	`+ * @param Integer $n`
	`14`	`+ * @return TreeNode[]`
	`15`	`+ */`
	`16`	`+ function generateTrees($n) {`
	`17`	`+ if ($n == 0) {`
	`18`	`+ return [];`
	`19`	`+ }`
	`20`	`+ $results = self::helper(1, $n);`
	`21`	`+ return $results;`
	`22`	`+ }`
	`23`	`+`
	`24`	`+ function helper($begin, $end) {`
	`25`	`+ $results = [];`
	`26`	`+ if ($begin > $end) {`
	`27`	`+ array_push($results, null);`
	`28`	`+ return $results;`
	`29`	`+ }`
	`30`	`+ if ($begin == $end) {`
	`31`	`+ array_push($results, new TreeNode($begin));`
	`32`	`+ return $results;`
	`33`	`+ }`
	`34`	`+`
	`35`	`+ for ($i = $begin; $i <= $end; $i++) {`
	`36`	`+ $lstLeft = self::helper($begin, $i - 1);`
	`37`	`+ $lstRight = self::helper($i + 1, $end);`
	`38`	`+`
	`39`	`+ for ($j = 0; $j < count($lstLeft); $j++) {`
	`40`	`+ $lNode = $lstLeft[$j];`
	`41`	`+ for ($k = 0; $k < count($lstRight); $k++) {`
	`42`	`+ $rNode = $lstRight[$k];`
	`43`	`+ $root = new TreeNode($i);`
	`44`	`+ $root->left = $lNode;`
	`45`	`+ $root->right = $rNode;`
	`46`	`+ array_push($results, $root);`
	`47`	`+ }`
	`48`	`+ }`
	`49`	`+ }`
	`50`	`+ return $results;`
	`51`	`+ }`
	`52`	`+}`

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