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66 lines
1.5 KiB
66 lines
1.5 KiB
"""
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File: binary_tree_dfs.py
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Created Time: 2022-12-20
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Author: a16su (lpluls001@gmail.com)
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"""
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import sys
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from pathlib import Path
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sys.path.append(str(Path(__file__).parent.parent))
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from modules import TreeNode, list_to_tree, print_tree
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def pre_order(root: TreeNode | None):
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"""前序走訪"""
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if root is None:
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return
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# 訪問優先順序：根節點 -> 左子樹 -> 右子樹
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res.append(root.val)
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pre_order(root=root.left)
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pre_order(root=root.right)
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def in_order(root: TreeNode | None):
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"""中序走訪"""
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if root is None:
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return
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# 訪問優先順序：左子樹 -> 根節點 -> 右子樹
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in_order(root=root.left)
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res.append(root.val)
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in_order(root=root.right)
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def post_order(root: TreeNode | None):
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"""後序走訪"""
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if root is None:
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return
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# 訪問優先順序：左子樹 -> 右子樹 -> 根節點
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post_order(root=root.left)
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post_order(root=root.right)
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res.append(root.val)
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"""Driver Code"""
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if __name__ == "__main__":
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# 初始化二元樹
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# 這裡藉助了一個從陣列直接生成二元樹的函式
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root = list_to_tree(arr=[1, 2, 3, 4, 5, 6, 7])
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print("\n初始化二元樹\n")
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print_tree(root)
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# 前序走訪
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res = []
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pre_order(root)
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print("\n前序走訪的節點列印序列 = ", res)
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# 中序走訪
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res.clear()
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in_order(root)
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print("\n中序走訪的節點列印序列 = ", res)
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# 後序走訪
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res.clear()
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post_order(root)
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print("\n後序走訪的節點列印序列 = ", res)
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