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120 lines
3.5 KiB
Python
120 lines
3.5 KiB
Python
"""
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File: array_binary_tree.py
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Created Time: 2023-07-19
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Author: krahets (krahets@163.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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class ArrayBinaryTree:
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"""Binary tree class represented by array"""
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def __init__(self, arr: list[int | None]):
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"""Constructor"""
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self._tree = list(arr)
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def size(self):
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"""List capacity"""
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return len(self._tree)
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def val(self, i: int) -> int | None:
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"""Get value of node at index i"""
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# If index is out of bounds, return None, representing empty position
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if i < 0 or i >= self.size():
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return None
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return self._tree[i]
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def left(self, i: int) -> int | None:
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"""Get index of left child node of node at index i"""
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return 2 * i + 1
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def right(self, i: int) -> int | None:
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"""Get index of right child node of node at index i"""
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return 2 * i + 2
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def parent(self, i: int) -> int | None:
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"""Get index of parent node of node at index i"""
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return (i - 1) // 2
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def level_order(self) -> list[int]:
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"""Level-order traversal"""
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self.res = []
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# Traverse array directly
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for i in range(self.size()):
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if self.val(i) is not None:
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self.res.append(self.val(i))
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return self.res
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def dfs(self, i: int, order: str):
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"""Depth-first traversal"""
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if self.val(i) is None:
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return
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# Preorder traversal
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if order == "pre":
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self.res.append(self.val(i))
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self.dfs(self.left(i), order)
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# Inorder traversal
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if order == "in":
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self.res.append(self.val(i))
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self.dfs(self.right(i), order)
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# Postorder traversal
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if order == "post":
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self.res.append(self.val(i))
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def pre_order(self) -> list[int]:
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"""Preorder traversal"""
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self.res = []
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self.dfs(0, order="pre")
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return self.res
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def in_order(self) -> list[int]:
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"""Inorder traversal"""
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self.res = []
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self.dfs(0, order="in")
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return self.res
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def post_order(self) -> list[int]:
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"""Postorder traversal"""
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self.res = []
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self.dfs(0, order="post")
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return self.res
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"""Driver Code"""
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if __name__ == "__main__":
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# Initialize binary tree
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# Here we use a function to generate a binary tree directly from an array
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arr = [1, 2, 3, 4, None, 6, 7, 8, 9, None, None, 12, None, None, 15]
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root = list_to_tree(arr)
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print("\nInitialize binary tree\n")
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print("Array representation of binary tree:")
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print(arr)
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print("Linked list representation of binary tree:")
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print_tree(root)
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# Binary tree class represented by array
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abt = ArrayBinaryTree(arr)
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# Access nodes
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i = 1
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l, r, p = abt.left(i), abt.right(i), abt.parent(i)
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print(f"\nCurrent node's index is {i}, value is {abt.val(i)}")
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print(f"Its left child node's index is {l}, value is {abt.val(l)}")
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print(f"Its right child node's index is {r}, value is {abt.val(r)}")
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print(f"Its parent node's index is {p}, value is {abt.val(p)}")
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# Traverse tree
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res = abt.level_order()
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print("\nLevel-order traversal is:", res)
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res = abt.pre_order()
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print("Preorder traversal is:", res)
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res = abt.in_order()
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print("Inorder traversal is:", res)
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res = abt.post_order()
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print("Postorder traversal is:", res)
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