add 095

Author: shishishu

README.md

@@ -38,5 +38,5 @@ Idx | Date | Question | Python| Java | Domain | Tag | Difficulty | Remark
 032|20200406|[226. Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/)|[226p](https://github.com/shishishu/leetcode-python-java/blob/master/ipynb_files/226_Invert_Binary_Tree.ipynb)|[226j](https://github.com/shishishu/leetcode-python-java/blob/master/java_codes/226/Solution.java)|Tree|Recursive/Iterative|Easy
 033|20200406|[110. Balanced Binary Tree](https://leetcode.com/problems/balanced-binary-tree/)|[110p](https://github.com/shishishu/leetcode-python-java/blob/master/ipynb_files/110_Balanced_Binary_Tree.ipynb)|[110j](https://github.com/shishishu/leetcode-python-java/blob/master/java_codes/110/Solution.java)|Tree|Recursive|Easy
 034|20200406|[96. Unique Binary Search Trees](https://leetcode.com/problems/unique-binary-search-trees/)|[096p](https://github.com/shishishu/leetcode-python-java/blob/master/ipynb_files/096_Unique_Binary_Search_Trees.ipynb)|[096j](https://github.com/shishishu/leetcode-python-java/blob/master/java_codes/096/Solution.java)|BST|DP|Medium
-
+035|20200406|[95. Unique Binary Search Trees II](https://leetcode.com/problems/unique-binary-search-trees-ii/)|[095p](https://github.com/shishishu/leetcode-python-java/blob/master/ipynb_files/095_Unique_Binary_Search_Trees_II.ipynb)|[095j](https://github.com/shishishu/leetcode-python-java/blob/master/java_codes/095/Solution.java)|BST|DP|Medium
 

images/095_Q.PNG

@@ -0,0 +1,78 @@
+import java.util.ArrayList;
+import java.util.List;
+
+class TreeNode {
+    int val;
+    TreeNode left;
+    TreeNode right;
+    TreeNode(int x) {
+        val = x;
+    }
+}
+
+// DP
+class Solution {
+    public List<TreeNode> generateTrees(int n) {
+        List<TreeNode>[] res = new List[n+1];
+        res[0] = new ArrayList<TreeNode>();
+        if (n == 0){
+            return res[0];
+        }
+        res[0].add(null);
+        res[1] = new ArrayList<TreeNode>();
+        res[1].add(new TreeNode(1));
+        for (int i=2; i <=n ; i++){
+            res[i] = new ArrayList<TreeNode>();
+            for (int j=1; j<=i; j++){
+                for (TreeNode nodeL: res[j - 1]){
+                    for (TreeNode nodeR: res[i - j]){
+                        TreeNode node = new TreeNode(j);
+                        node.left = nodeL;
+                        node.right = cloneTrees(nodeR, j);
+                        res[i].add(node);
+                    }
+                }
+            }
+        }
+        return res[n];
+    }
+
+    public TreeNode cloneTrees(TreeNode node, int offset){
+        if (node == null){
+            return null;
+        }
+        TreeNode newNode = new TreeNode(node.val + offset);
+        newNode.left = cloneTrees(node.left, offset);
+        newNode.right = cloneTrees(node.right, offset);
+        return newNode;
+    }
+}
+
+// Recursive
+class Solution {
+    public List<TreeNode> generateTrees(int n) {
+        return (n == 0)?new ArrayList<TreeNode>(): geneTrees(1, n);
+    }
+
+    public TreeNode formatNode(int val, TreeNode left, TreeNode right){
+        TreeNode newNode = new TreeNode(val);
+        newNode.left = left;
+        newNode.right = right;
+        return newNode;
+    }
+
+    public List<TreeNode> geneTrees(int lo, int hi){
+        List<TreeNode> res = new ArrayList<TreeNode>();
+        for (int i=lo; i<=hi; i++){
+            for(TreeNode nodeL: geneTrees(lo, i - 1)){
+                for (TreeNode nodeR: geneTrees(i + 1, hi)){
+                    res.add(formatNode(i, nodeL, nodeR));
+                }
+            }
+        }
+        if (res.isEmpty()){
+            res.add(null);
+        }
+        return res;
+    }
+}

images/095_S1.PNG

@@ -38,6 +38,7 @@
       <sourceFolder url="file://$MODULE_DIR$/226" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/110" isTestSource="false" />
       <sourceFolder url="file://$MODULE_DIR$/096" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/095" isTestSource="false" />
     </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />