Merge pull request #3674 from Srihari2222/develop_articles

Sri Hari: Batch-2/Neetcode-150/articles

Author: neetcode-gh

articles/balanced-binary-tree.md

@@ -0,0 +1,398 @@
+## 1. Depth First Search
+
+::tabs-start
+
+```python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+
+class Solution:
+    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
+        res = []
+
+        def dfs(node, depth):
+            if not node:
+                return None
+            if depth == len(res):
+                res.append(node.val)
+            
+            dfs(node.right, depth + 1)
+            dfs(node.left, depth + 1)
+        
+        dfs(root, 0)
+        return res
+```
+
+```java
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+
+public class Solution {
+    List<Integer> res = new ArrayList<>();
+    
+    public List<Integer> rightSideView(TreeNode root) {
+        dfs(root, 0);
+        return res;
+    }
+    
+    private void dfs(TreeNode node, int depth) {
+        if (node == null) {
+            return;
+        }
+        
+        if (res.size() == depth) {
+            res.add(node.val);
+        }
+        
+        dfs(node.right, depth + 1);
+        dfs(node.left, depth + 1);
+    }
+}
+```
+
+```cpp
+/**
+ * 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:
+    vector<int> res;
+    
+    vector<int> rightSideView(TreeNode* root) {
+        dfs(root, 0);
+        return res;
+    }
+    
+    void dfs(TreeNode* node, int depth) {
+        if (!node) return;
+        
+        if (res.size() == depth) {
+            res.push_back(node->val);
+        }
+        
+        dfs(node->right, depth + 1);
+        dfs(node->left, depth + 1);
+    }
+};
+```
+
+```javascript
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     constructor(val = 0, left = null, right = null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+
+class Solution {
+    /**
+     * @param {TreeNode} root
+     * @return {number[]}
+     */
+    rightSideView(root) {
+        let res = [];
+
+        function dfs(node, depth) {
+            if (!node) return;
+
+            if (res.length === depth) {
+                res.push(node.val);
+            }
+
+            dfs(node.right, depth + 1);
+            dfs(node.left, depth + 1);
+        }
+
+        dfs(root, 0);
+        return res;
+    }
+}
+```
+
+```csharp
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+
+public class Solution {
+    List<int> res = new List<int>();
+    
+    public List<int> RightSideView(TreeNode root) {
+        dfs(root, 0);
+        return res;
+    }
+    
+    private void dfs(TreeNode node, int depth) {
+        if (node == null) {
+            return;
+        }
+        
+        if (res.Count == depth) {
+            res.Add(node.val);
+        }
+        
+        dfs(node.right, depth + 1);
+        dfs(node.left, depth + 1);
+    }
+}
+```
+
+::tabs-end
+
+### Time & Space Complexity
+
+* Time complexity: $O(n)$
+* Space complexity: $O(n)$
+
+---
+
+## 2. Breadth First Search
+
+::tabs-start
+
+```python
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+
+class Solution:
+    def rightSideView(self, root: Optional[TreeNode]) -> List[int]:
+        res = []
+        q = deque([root])
+
+        while q:
+            rightSide = None
+            qLen = len(q)
+
+            for i in range(qLen):
+                node = q.popleft()
+                if node:
+                    rightSide = node
+                    q.append(node.left)
+                    q.append(node.right)
+            if rightSide:
+                res.append(rightSide.val)
+        return res
+```
+
+```java
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+
+class Solution {
+    public List<Integer> rightSideView(TreeNode root) {
+        List<Integer> res = new ArrayList<>();
+        Queue<TreeNode> q = new LinkedList<>();
+        q.offer(root);
+
+        while (!q.isEmpty()) {
+            TreeNode rightSide = null;
+            int qLen = q.size();
+
+            for (int i = 0; i < qLen; i++) {
+                TreeNode node = q.poll();
+                if (node != null) {
+                    rightSide = node;
+                    q.offer(node.left);
+                    q.offer(node.right);
+                }
+            }
+            if (rightSide != null) {
+                res.add(rightSide.val);
+            }
+        }
+        return res;
+    }
+}
+```
+
+```cpp
+/**
+ * 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:
+    vector<int> rightSideView(TreeNode* root) {
+        vector<int> res;
+        queue<TreeNode*> q;
+        q.push(root);
+
+        while (!q.empty()) {
+            TreeNode* rightSide = nullptr;
+            int qLen = q.size();
+
+            for (int i = 0; i < qLen; i++) {
+                TreeNode* node = q.front();
+                q.pop();
+                if (node) {
+                    rightSide = node;
+                    q.push(node->left);
+                    q.push(node->right);
+                }
+            }
+            if (rightSide) {
+                res.push_back(rightSide->val);
+            }
+        }
+        return res;
+    }
+};
+```
+
+```javascript
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     constructor(val = 0, left = null, right = null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+
+class Solution {
+    /**
+     * @param {TreeNode} root
+     * @return {number[]}
+     */
+    rightSideView(root) {
+        const res = [];
+        const q = new Queue();
+
+        q.push(root);
+
+        while (!q.isEmpty()) {
+            let rightSide = null;
+            const qLen = q.size();
+
+            for (let i = 0; i < qLen; i++) {
+                const node = q.pop();
+                if (node) {
+                    rightSide = node;
+                    q.push(node.left);
+                    q.push(node.right);
+                }
+            }
+            if (rightSide) {
+                res.push(rightSide.val);
+            }
+        }
+        return res;
+    }
+}
+```
+
+```csharp
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     public int val;
+ *     public TreeNode left;
+ *     public TreeNode right;
+ *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+
+public class Solution {
+    public List<int> RightSideView(TreeNode root) {
+        List<int> res = new List<int>();
+        Queue<TreeNode> q = new Queue<TreeNode>();
+        q.Enqueue(root);
+
+        while (q.Count > 0) {
+            TreeNode rightSide = null;
+            int qLen = q.Count;
+
+            for (int i = 0; i < qLen; i++) {
+                TreeNode node = q.Dequeue();
+                if (node != null) {
+                    rightSide = node;
+                    q.Enqueue(node.left);
+                    q.Enqueue(node.right);
+                }
+            }
+            if (rightSide != null) {
+                res.Add(rightSide.val);
+            }
+        }
+        return res;
+    }
+}
+```
+
+::tabs-end
+
+### Time & Space Complexity
+
+* Time complexity: $O(n)$
+* Space complexity: $O(n)$