51 lines
1.2 KiB
C++
51 lines
1.2 KiB
C++
#include <iostream>
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#include <stack>
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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 x) : val(x), left(nullptr), right(nullptr) {}
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};
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// pre order traverse a binary tree, iteratively.
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void postorderTraversal(TreeNode* root) {
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if (root == nullptr) return;
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std::stack<TreeNode*> st1, st2;
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st1.push(root);
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while (!st1.empty()) {
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TreeNode* current = st1.top();
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st1.pop();
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st2.push(current);
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if (current->left) st1.push(current->left);
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if (current->right) st1.push(current->right);
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}
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while (!st2.empty()) {
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std::cout << st2.top()->val << " ";
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st2.pop();
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}
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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 << "Inorder Traversal: ";
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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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