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66 lines
1.6 KiB
Python
66 lines
1.6 KiB
Python
"""
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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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"""先行順走査"""
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if root is None:
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return
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# 訪問順序：根ノード -> 左部分木 -> 右部分木
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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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"""中順走査"""
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if root is None:
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return
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# 訪問優先順: 左部分木 -> 根ノード -> 右部分木
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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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"""後順走査"""
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if root is None:
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return
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# 訪問優先順: 左部分木 -> 右部分木 -> 根ノード
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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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# 二分木を初期化
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# ここでは、配列から直接二分木を生成する関数を利用する
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root = list_to_tree(arr=[1, 2, 3, 4, 5, 6, 7])
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print("\n二分木を初期化\n")
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print_tree(root)
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# 先行順走査
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res = []
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pre_order(root)
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print("\n先行順走査のノード出力シーケンス = ", res)
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# 中順走査
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res.clear()
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in_order(root)
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print("\n中間順走査のノード出力シーケンス = ", res)
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# 後順走査
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res.clear()
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post_order(root)
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print("\n後行順走査のノード出力シーケンス = ", res)
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