79 lines
2.1 KiB
C++
79 lines
2.1 KiB
C++
#include <iostream>
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#include <queue>
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class Node {
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public:
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int value;
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Node* left;
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Node* right;
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// constructor to create a new node
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Node(int val) : value(val), left(NULL), right(NULL) {}
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};
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// the breadth-first traversal function using std::queue
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void breadth_first_traverse(Node* root) {
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if (root == NULL) {
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return;
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}
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std::queue<Node*> node_queue; // queue to store nodes for BFS traversal
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node_queue.push(root); // start by pushing the root node
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int level = 0;
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while (!node_queue.empty()) {
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int level_size = node_queue.size(); // number of nodes at the current level
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std::cout << "level " << level << ": ";
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for (int i = 0; i < level_size; i++) {
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Node* current_node = node_queue.front(); // get the front node
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node_queue.pop(); // remove the node from the queue
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std::cout << current_node->value << " "; // print the value of the node
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// push the children of the current node to the queue (if they exist)
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if (current_node->left != NULL) {
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node_queue.push(current_node->left);
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}
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if (current_node->right != NULL) {
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node_queue.push(current_node->right);
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}
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}
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// after we finish the for loop, the only pointers in the queue, are the pointers pointing to nodes of the next level.
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std::cout << std::endl;
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level++;
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}
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}
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int main() {
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// creating a simple binary tree
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// 1
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// / \
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// 2 3
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// / \ / \
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//4 5 6 7
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Node* root = new Node(1);
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root->left = new Node(2);
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root->right = new Node(3);
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root->left->left = new Node(4);
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root->left->right = new Node(5);
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root->right->left = new Node(6);
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root->right->right = new Node(7);
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// calling the breadth-first traversal function
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breadth_first_traverse(root);
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// cleaning up dynamically allocated memory
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delete root->left->left;
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delete root->left->right;
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delete root->right->left;
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delete root->right->right;
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delete root->left;
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delete root->right;
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delete root;
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return 0;
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}
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