63 lines
1.5 KiB
Dart
63 lines
1.5 KiB
Dart
/**
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* File: binary_tree_dfs.dart
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* Created Time: 2023-04-04
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* Author: liuyuxin (gvenusleo@gmail.com)
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*/
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import '../utils/print_util.dart';
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import '../utils/tree_node.dart';
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// Initialize the list for storing traversal sequences
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List<int> list = [];
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/* Pre-order traversal */
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void preOrder(TreeNode? node) {
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if (node == null) return;
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// Visit priority: root node -> left subtree -> right subtree
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list.add(node.val);
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preOrder(node.left);
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preOrder(node.right);
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}
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/* In-order traversal */
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void inOrder(TreeNode? node) {
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if (node == null) return;
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// Visit priority: left subtree -> root node -> right subtree
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inOrder(node.left);
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list.add(node.val);
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inOrder(node.right);
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}
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/* Post-order traversal */
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void postOrder(TreeNode? node) {
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if (node == null) return;
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// Visit priority: left subtree -> right subtree -> root node
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postOrder(node.left);
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postOrder(node.right);
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list.add(node.val);
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}
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/* Driver Code */
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void main() {
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/* Initialize binary tree */
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// Use a specific function to convert an array into a binary tree
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TreeNode? root = listToTree([1, 2, 3, 4, 5, 6, 7]);
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print("\nInitialize binary tree\n");
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printTree(root);
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/* Pre-order traversal */
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list.clear();
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preOrder(root);
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print("\nPrint sequence of nodes in pre-order traversal = $list");
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/* In-order traversal */
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list.clear();
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inOrder(root);
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print("\nPrint sequence of nodes in in-order traversal = $list");
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/* Post-order traversal */
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list.clear();
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postOrder(root);
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print("\nPrint sequence of nodes in post-order traversal = $list");
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}
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