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

Author: Abe0770

Diff for: cpp/0116-populating-next-right-pointers-in-each-node.cpp

@@ -0,0 +1,69 @@
+/*
+  You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:
+  
+  struct Node {
+    int val;
+    Node *left;
+    Node *right;
+    Node *next;
+  }
+  
+  Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL.
+  Initially, all next pointers are set to NULL.
+
+  Ex. Input: root = [1,2,3,4,5,6,7]
+      Output: [1,#,2,3,#,4,5,6,7,#]
+      Explanation: Given the above perfect binary tree (Figure A), your function should populate each next pointer to point to its next right node,
+      just like in Figure B. The serialized output is in level order as connected by the next pointers, with '#' signifying the end of each level.
+
+  Time  : O(N)
+  Space : O(N)
+*/
+
+/*
+// 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 == NULL || (root -> right == NULL && root -> left == NULL))
+            return root;
+        queue <Node*>q;
+        q.push(root);
+
+        while(!q.empty()) {
+            int size = q.size();
+            Node* temp = NULL;
+
+            for(int i = 0 ; i < size ; i++) {
+                Node* front = q.front();
+
+                if(temp != NULL)
+                    temp -> next = front;
+                temp = front;
+
+                if(front -> left) {
+                    q.push(front -> left);
+                    q.push(front -> right);
+                }
+                q.pop();
+            }
+        }
+        return root;
+    }
+};