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64 lines
1.5 KiB
64 lines
1.5 KiB
/**
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* File: binary_tree_dfs.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_tree
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import utils.TreeNode
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import utils.printTree
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// 初始化串列，用於儲存走訪序列
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var list = mutableListOf<Int>()
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/* 前序走訪 */
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fun preOrder(root: TreeNode?) {
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if (root == null) return
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// 訪問優先順序：根節點 -> 左子樹 -> 右子樹
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list.add(root._val)
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preOrder(root.left)
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preOrder(root.right)
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}
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/* 中序走訪 */
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fun inOrder(root: TreeNode?) {
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if (root == null) return
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// 訪問優先順序：左子樹 -> 根節點 -> 右子樹
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inOrder(root.left)
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list.add(root._val)
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inOrder(root.right)
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}
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/* 後序走訪 */
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fun postOrder(root: TreeNode?) {
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if (root == null) return
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// 訪問優先順序：左子樹 -> 右子樹 -> 根節點
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postOrder(root.left)
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postOrder(root.right)
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list.add(root._val)
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}
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/* Driver Code */
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fun main() {
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/* 初始化二元樹 */
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// 這裡藉助了一個從串列直接生成二元樹的函式
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val root = TreeNode.listToTree(mutableListOf(1, 2, 3, 4, 5, 6, 7))
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println("\n初始化二元樹\n")
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printTree(root)
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/* 前序走訪 */
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list.clear()
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preOrder(root)
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println("\n前序走訪的節點列印序列 = $list")
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/* 中序走訪 */
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list.clear()
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inOrder(root)
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println("\n中序走訪的節點列印序列 = $list")
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/* 後序走訪 */
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list.clear()
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postOrder(root)
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println("\n後序走訪的節點列印序列 = $list")
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} |