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52 lines
1.2 KiB
52 lines
1.2 KiB
/**
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* File: preorder_traversal_iii_compact.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_backtracking.preorder_traversal_iii_compact
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import utils.TreeNode
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import utils.printTree
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var path: MutableList<TreeNode>? = null
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var res: MutableList<MutableList<TreeNode>>? = null
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/* 前序遍历：例题三 */
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fun preOrder(root: TreeNode?) {
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// 剪枝
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if (root == null || root._val == 3) {
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return
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}
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// 尝试
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path!!.add(root)
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if (root._val == 7) {
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// 记录解
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res!!.add(path!!.toMutableList())
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}
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preOrder(root.left)
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preOrder(root.right)
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// 回退
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path!!.removeAt(path!!.size - 1)
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}
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/* Driver Code */
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fun main() {
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val root = TreeNode.listToTree(mutableListOf(1, 7, 3, 4, 5, 6, 7))
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println("\n初始化二叉树")
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printTree(root)
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// 前序遍历
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path = mutableListOf()
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res = mutableListOf()
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preOrder(root)
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println("\n输出所有根节点到节点 7 的路径，路径中不包含值为 3 的节点")
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for (path in res!!) {
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val _vals = mutableListOf<Int>()
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for (node in path) {
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_vals.add(node._val)
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}
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println(_vals)
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}
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} |