Merge pull request #124 from PrakashShukla0907/add-time-to-burn-binary-tree

Added Time to Burn Binary Tree implementation in C++ under CPP/tree/

Author: admirerr

CPP/tree/binary_tree.exe

@@ -0,0 +1,130 @@
+#include <iostream>
+#include <queue>
+#include <unordered_map>
+#include <unordered_set>
+using namespace std;
+
+
+// Definition for a binary tree node.
+struct Node  
+{
+ int data;
+ Node *left;
+ Node *right;
+ Node(int val)
+ {
+  data = val;
+  left = NULL;
+  right = NULL;
+ }
+};
+
+// Function to build the binary tree from user input
+// Input format: Enter node values in pre-order fashion. Use -1 to indicate NULL nodes
+Node *buildTree()
+{
+ int val;
+ cin >> val;
+ if (val == -1)
+  return NULL;
+ Node *root = new Node(val);
+ root->left = buildTree();
+ root->right = buildTree();
+ return root;
+}
+
+void markParent(Node *root, unordered_map<Node *, Node *> &parent_track)
+{
+ queue<Node *> q;
+ q.push(root);
+ while (!q.empty())
+ {
+  Node *curr = q.front();
+  q.pop();
+  if (curr->left)
+  {
+   parent_track[curr->left] = curr;
+   q.push(curr->left);
+  }
+  if (curr->right)
+  {
+   parent_track[curr->right] = curr;
+   q.push(curr->right);
+  }
+ }
+}
+
+// Function to calculate the time to burn the binary tree from the target node
+int timeToBurnTree(Node *root, int target)
+{
+ unordered_map<Node *, Node *> parent_track;
+ markParent(root, parent_track);
+ queue<Node *> q;
+ unordered_set<Node *> visited;
+ int time = 0;
+ // find the target node
+ Node *targetNode = NULL;
+ for (auto it : parent_track)
+ {
+  if (it.first->data == target)
+  {
+   targetNode = it.first;
+   break;
+  }
+ }
+ if (targetNode == NULL)
+  return -1; // target not found
+ q.push(targetNode);
+ visited.insert(targetNode);
+ while (!q.empty())
+ {
+  int size = q.size();
+  bool flag = false; // to check if any new node is burned in this time unit
+  for (int i = 0; i < size; i++)
+  {
+   Node *curr = q.front();
+   q.pop();
+   if (curr->left && visited.find(curr->left) == visited.end())
+   {
+    flag = true;
+    visited.insert(curr->left);
+    q.push(curr->left);
+   }
+   if (curr->right && visited.find(curr->right) == visited.end())
+   {
+    flag = true;
+    visited.insert(curr->right);
+    q.push(curr->right);
+   }
+   if (parent_track.find(curr) != parent_track.end() && visited.find(parent_track[curr]) == visited.end())
+   {
+    flag = true;
+    visited.insert(parent_track[curr]);
+    q.push(parent_track[curr]);
+   }
+  }
+  if (flag)
+   time++;
+ }
+ return time;
+}
+
+// Input format for building the tree:
+// Enter node values in pre-order fashion. Use -1 to indicate NULL nodes. 
+// Example: 1 2 4 -1 -1 5 -1 -1 3 -1 -1 (represents the tree below)
+//target = 2
+//time = 2 seconds
+//target = 3
+//time = 3 seconds
+
+int main()
+{
+ cout << "Build the binary tree (use -1 for NULL nodes): ";
+ Node *root = buildTree();
+ cout << "Enter target node value: ";
+ int target;
+ cin >> target;
+ cout << "Time to burn the tree: ";
+ cout << timeToBurnTree(root, target) << endl;
+ return 0;
+}