added 116, 117, 173

Author: rustykitty

0116-populating-next-right-pointers-in-each-node.cpp

@@ -0,0 +1,42 @@
+/*
+116. Populating Next Right Pointers in Each Node
+
+Submitted: December 8, 2024
+
+Runtime: 11 ms (beats 82.54%)
+Memory: 18.81 MB (beats 73.03%)
+*/
+
+/*
+// Definition for a Node.
+class Node {
+public:
+    int val;
+    Node* left;
+    Node* right;
+    Node* next;
+
+    Node() : val(0), left(NULL), right(NULL), next(NULL) {}
+
+    Node(int _val) : val(_val), left(NULL), right(NULL), next(NULL) {}
+
+    Node(int _val, Node* _left, Node* _right, Node* _next)
+        : val(_val), left(_left), right(_right), next(_next) {}
+};
+*/
+
+class Solution {
+public:
+    Node* connect(Node* root) {
+        if (root == nullptr) return nullptr;
+        if (root->left == nullptr) return root;
+        root->left->next = root->right;
+        for (Node* p = root; p->next != nullptr; ) {
+            p->right->next = p->next->left;
+            p = p->next;
+            p->left->next = p->right;
+        }
+        connect(root->left);
+        return root;
+    }
+};

0117-populating-next-right-pointers-in-each-node-ii.cpp

@@ -0,0 +1,45 @@
+/*
+116. Populating Next Right Pointers in Each Node
+
+Submitted: December 8, 2024
+
+Runtime: 11 ms (beats 48.73%)
+Memory: 18.80 MB (beats 35.89%)
+*/
+
+/*
+// Definition for a Node.
+class Node {
+public:
+    int val;
+    Node* left;
+    Node* right;
+    Node* next;
+
+    Node() : val(0), left(NULL), right(NULL), next(NULL) {}
+
+    Node(int _val) : val(_val), left(NULL), right(NULL), next(NULL) {}
+
+    Node(int _val, Node* _left, Node* _right, Node* _next)
+        : val(_val), left(_left), right(_right), next(_next) {}
+};
+*/
+
+class Solution {
+public:
+    Node* connect(Node* root) {
+        if (root == nullptr) return nullptr;
+        deque<Node*> queue;
+        queue.push_back(root);
+        while (!queue.empty()) {
+            for (int i = 0, n = queue.size(); i < n; ++i) {
+                Node* p = queue.back();
+                queue.pop_back();
+                if (i < n - 1) p->next = queue.back();
+                if (p->left != nullptr) queue.push_front(p->left);
+                if (p->right != nullptr) queue.push_front(p->right);
+            }
+        }
+        return root;
+    }
+};

0173-binary-search-tree-iterator.cpp

@@ -0,0 +1,51 @@
+/*
+173. Binary Search Tree Iterator
+
+Submitted: December 8, 2024
+
+Runtime: 3 ms (beats 70.78%)
+Memory: 32.22 MB (beats 6.21%)
+*/
+
+/**
+ * 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 BSTIterator {
+private:
+    vector<int> arr;
+    vector<int>::const_iterator pos;
+    void traverse(TreeNode* root) {
+        if (root == nullptr) return;
+        traverse(root->left);
+        arr.push_back(root->val);
+        traverse(root->right);
+    }
+public:
+    BSTIterator(TreeNode* root) {
+        traverse(root);
+        pos = arr.cbegin();
+    }
+    
+    int next() {
+        return *pos++;
+    }
+    
+    bool hasNext() {
+        return pos != arr.cend();
+    }
+};
+
+/**
+ * Your BSTIterator object will be instantiated and called as such:
+ * BSTIterator* obj = new BSTIterator(root);
+ * int param_1 = obj->next();
+ * bool param_2 = obj->hasNext();
+ */