day 2

Author: sachuverma

Leetcode Daily Challenge/February-2021/02. Trim a Binary Search Tree.cpp

@@ -0,0 +1,70 @@
+/*
+Trim a Binary Search Tree
+=========================
+
+Given the root of a binary search tree and the lowest and highest boundaries as low and high, trim the tree so that all its elements lies in [low, high]. Trimming the tree should not change the relative structure of the elements that will remain in the tree (i.e., any node's descendant should remain a descendant). It can be proven that there is a unique answer.
+
+Return the root of the trimmed binary search tree. Note that the root may change depending on the given bounds.
+
+Example 1:
+Input: root = [1,0,2], low = 1, high = 2
+Output: [1,null,2]
+
+Example 2:
+Input: root = [3,0,4,null,2,null,null,1], low = 1, high = 3
+Output: [3,2,null,1]
+
+Example 3:
+Input: root = [1], low = 1, high = 2
+Output: [1]
+
+Example 4:
+Input: root = [1,null,2], low = 1, high = 3
+Output: [1,null,2]
+
+Example 5:
+Input: root = [1,null,2], low = 2, high = 4
+Output: [2]
+
+Constraints:
+The number of nodes in the tree in the range [1, 104].
+0 <= Node.val <= 104
+The value of each node in the tree is unique.
+root is guaranteed to be a valid binary search tree.
+0 <= low <= high <= 104
+*/
+
+/**
+ * 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 *trimBST(TreeNode *root, int low, int high)
+  {
+    if (!root)
+      return root;
+
+    auto left = trimBST(root->left, low, high);
+    auto right = trimBST(root->right, low, high);
+
+    root->left = left;
+    root->right = right;
+
+    if (root->val < low)
+      return right;
+    else if (root->val > high)
+      return left;
+
+    return root;
+  }
+};

Leetcode Daily Challenge/February-2021/README.MD

@@ -3,6 +3,6 @@
 | Day | Question Links | Solutions |
 | :-: | :------------- | :-------: |
 | 1.  | [Number of 1 Bits](https://leetcode.com/explore/challenge/card/february-leetcoding-challenge-2021/584/week-1-february-1st-february-7th/3625/) | [cpp](./01.%20Number%20of%201%20Bits.cpp) |
-| 2.  | []() | [cpp](./02.%20.cpp) |
+| 2.  | [Trim a Binary Search Tree](https://leetcode.com/explore/challenge/card/february-leetcoding-challenge-2021/584/week-1-february-1st-february-7th/3626/) | [cpp](./02.%20Trim%20a%20Binary%20Search%20Tree.cpp) |
 | 3.  | [Linked List Cycle](https://leetcode.com/explore/challenge/card/february-leetcoding-challenge-2021/584/week-1-february-1st-february-7th/3627/) | [cpp](./03.%20Linked%20List%20Cycle.cpp) |
 | 4.  | [Longest Harmonious Subsequence](https://leetcode.com/explore/challenge/card/february-leetcoding-challenge-2021/584/week-1-february-1st-february-7th/3628/) | [cpp](./04.%20Longest%20Harmonious%20Subsequence.cpp) |