84 lines
2.2 KiB
C++
84 lines
2.2 KiB
C++
#include <iostream>
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class TreeNode {
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public:
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int val;
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TreeNode* left;
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TreeNode* right;
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TreeNode(int value) : val(value), left(NULL), right(NULL) {}
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};
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// function to reverse the right-edge path of a subtree
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TreeNode* reverse(TreeNode* head) {
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TreeNode* prev = nullptr;
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TreeNode* next = nullptr;
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while (head != nullptr) {
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next = head->right;
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head->right = prev;
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prev = head;
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head = next;
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}
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return prev;
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}
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// function to traverse and collect nodes along a reversed right edge
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void reverseTraverseRightEdge(TreeNode* head) {
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TreeNode* tail = reverse(head);
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TreeNode* current = tail;
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while (current != nullptr) {
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std::cout << current->val << " ";
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current = current->right;
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}
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reverse(tail); // restore the original tree structure
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}
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// Morris Postorder Traversal
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void postorderTraversal(TreeNode* root) {
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TreeNode* current = root;
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TreeNode* rightmost;
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while (current != nullptr) {
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if (current->left != nullptr) {
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rightmost = current->left;
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while (rightmost->right != nullptr && rightmost->right != current) {
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rightmost = rightmost->right;
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}
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if (rightmost->right == nullptr) {
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rightmost->right = current;
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current = current->left;
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} else {
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rightmost->right = nullptr;
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reverseTraverseRightEdge(current->left);
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current = current->right;
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}
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} else {
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current = current->right;
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}
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}
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reverseTraverseRightEdge(root); // traverse the final right edge
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return;
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}
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int main() {
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TreeNode* root = new TreeNode(1);
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root->left = new TreeNode(2);
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root->right = new TreeNode(3);
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root->left->left = new TreeNode(4);
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root->left->right = new TreeNode(5);
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root->left->right->left = new TreeNode(6);
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root->left->right->right = new TreeNode(7);
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root->right->right = new TreeNode(8);
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root->right->right->left = new TreeNode(9);
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std::cout << "Postorder Traversal using Morris Traversal:\n";
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postorderTraversal(root);
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std::cout << std::endl;
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return 0;
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}
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