Generate all the BST

Given n, generate all structurally unique BST 's (binary search trees) that store values 1 ... n.

For example,
Given N = 3, your program should return all 5 unique BST ' s shown below.

   1         3     3      2      1    \//      /\           3     2     1      1   3      2    /     /       \                    2     1         2                 3

Analysis: For n, the valid BST has C (n,2*n)/(n+1)) species.

According to the post-order achievements, [1,.. I-1] I [i+1,.. N] First build the right and left to the legal BST, and then received root.

The left sub-tree form has m species, the right subtree has k species, then try to m*k the way of splicing.

Public list<treenode> generatetrees (int l, int r) {        list<treenode> List = new Arraylist<treenode> ( );        if (L > R) {            list.add (null);            return list;        }        for (int i = l; I <= R; i++) {            list<treenode> lefts = Generatetrees (l, i-1);            list<treenode> rights = Generatetrees (i + 1, r);            for (TreeNode left:lefts) {for                (TreeNode right:rights) {                    TreeNode root = new TreeNode (i);                    Root.left = left;                    Root.right = right;                    List.add (root);        }}} return list;    }    Public list<treenode> generatetrees (int n) {        return generatetrees (1, n);    }

Generate all the BST