Create 0701-insertion-into-a-binary-search-tree.cpp

Author: Abe0770

cpp/0701-insertion-into-a-binary-search-tree.cpp

@@ -0,0 +1,45 @@
+/*
+    You are given the root node of a binary search tree (BST) and a value to insert into the tree. 
+    Return the root node of the BST after the insertion. It is guaranteed that the new value does not exist in the original BST.
+
+    Notice that there may exist multiple valid ways for the insertion, as long as the tree remains a BST after insertion. 
+    You can return any of them.
+
+    Ex. Input: root = [4,2,7,1,3], val = 5
+        Output: [4,2,7,1,3,5]
+
+    Time  : O(N)
+    Space : O(N)
+*/
+
+/**
+ * Definition for a binary tree node.
+ * struct TreeNode {
+ *     int val;
+ *     TreeNode *left;
+ *     TreeNode *right;
+ *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+ *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+ * };
+ */
+class Solution {
+public:
+    TreeNode * create(int val) {
+        TreeNode *n = new TreeNode;
+        n -> val = val;
+        n -> left = n -> right = NULL;
+        return n;
+    }
+
+    TreeNode* insertIntoBST(TreeNode* root, int val) {
+        if(root == NULL) 
+		    return create(val);
+
+        else if(val > root -> val)
+		    root -> right = insertIntoBST(root -> right, val); 
+        else if(val < root -> val)
+		    root -> left = insertIntoBST(root -> left, val);
+	    return root;
+    }
+};