Merge pull request #619 from KBhushan07/main

Leetcode Binary Tree Solutions

Author: gantavyamalviya

Trees/Leetcode-116. Populating Next Right Pointers in Each Node.cpp

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    
+    Node* connect(Node* root) {
+        if(root==NULL)
+            return NULL;
+       
+        if(root->left){
+            root->left->next=root->right;
+        
+        if(root->next){
+            root->right->next=root->next->left;
+        }
+        
+        connect(root->left);
+        connect(root->right);
+        }
+        return root;
+        
+    }
+};

Trees/Leetcode-222. Count Complete Tree Nodes.cpp

@@ -0,0 +1,19 @@
+class Solution {
+public:
+    vector<int>num;
+    int countNodes(TreeNode* root) {
+        if(root==NULL)return 0;
+        queue<TreeNode*>q;
+        q.push(root);
+    while(!q.empty()){
+        TreeNode*curr = q.front();
+        num.push_back(curr->val);
+        if(curr->left!=NULL)
+            q.push(curr->left);
+        if(curr->right!=NULL)
+            q.push(curr->right);
+        q.pop();
+        }
+    return num.size();
+    }
+};

Trees/Leetcode-226. Invert Binary Tree.cpp

@@ -0,0 +1,8 @@
+TreeNode* invertTree(TreeNode* root) {
+    if (root) {
+        invertTree(root->left);
+        invertTree(root->right);
+        swap(root->left, root->right);
+    }
+    return root;
+}

Trees/Leetcode-230. Kth Smallest Element in a BST.cpp

@@ -0,0 +1,19 @@
+class Solution {
+public:
+    vector<int>num;
+    int kthSmallest(TreeNode* root, int k) {
+        queue<TreeNode*>q;
+        q.push(root);
+        while(!q.empty()){
+            TreeNode*curr = q.front();
+            num.push_back(curr->val);
+            if(curr->left!=NULL)
+                q.push(curr->left);
+            if(curr->right!=NULL)
+                q.push(curr->right);
+            q.pop();
+        }
+        sort(num.begin(), num.end());
+        return num[k-1];
+    }
+};

Trees/Leetcode-623. Add One Row to Tree.cpp

@@ -0,0 +1,82 @@
+/**
+ * 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:
+    
+    // getting all parent nodes for which we want to append nodes 
+    void getBfs(TreeNode* root, int depth , vector<TreeNode*>&v){
+        if(depth==1 && root!=NULL){
+            v.push_back(root);
+            return;
+        }
+        if(root==NULL)return;
+        
+        getBfs(root->left , depth-1 , v);
+        getBfs(root->right , depth-1 , v);
+        
+        return;
+    }
+    
+    //creating nodes
+    TreeNode* createNode(int val){
+        TreeNode *temp=new TreeNode;
+        temp->val = val;
+        return temp;
+    }
+    
+    
+    TreeNode* addOneRow(TreeNode* root, int val, int depth) {
+        
+        //if depth ==1
+        if(depth==1){
+            TreeNode* temp = createNode(val);
+            temp ->left = root;
+            return temp;
+        }
+        
+        
+        vector<TreeNode*>v;
+        getBfs(root , depth-1 , v);
+        int s = v.size();
+        
+        for(int i=0; i<s; i++){
+            TreeNode* temp1 = createNode(val);
+            TreeNode* temp2 = createNode(val);
+            TreeNode *t = v[i];
+            if(t->left && t->right){
+                temp1->left=t->left;
+                temp2->right=t->right;
+                t->left = temp1;
+                t->right = temp2;
+            }
+            else if(t->left && t->right==NULL){
+                temp1->left=t->left;
+                t->left = temp1;
+                t->right = temp2;
+            }
+            else if(t->left==NULL && t->right){
+                temp2->right=t->right;
+                t->left = temp1;
+                t->right = temp2;
+            }
+            else{
+                t->left = temp1;
+                t->right = temp2;
+            }
+        }
+        
+        
+        return root;
+        
+        
+    }
+};