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hello-algo/codes/kotlin/chapter_backtracking/preorder_traversal_i_compac...

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/**
* File: preorder_traversal_i_compact.kt
* Created Time: 2024-01-25
* Author: curtishd (1023632660@qq.com)
*/
package chapter_backtracking.preorder_traversal_i_compact
import utils.TreeNode
import utils.printTree
var res: MutableList<TreeNode>? = null
/* 前序遍历:例题一 */
fun preOrder(root: TreeNode?) {
if (root == null) {
return
}
if (root.value == 7) {
// 记录解
res!!.add(root)
}
preOrder(root.left)
preOrder(root.right)
}
/* Driver Code */
fun main() {
val root = TreeNode.listToTree(mutableListOf(1, 7, 3, 4, 5, 6, 7))
println("\n初始化二叉树")
printTree(root)
// 前序遍历
res = mutableListOf()
preOrder(root)
println("\n输出所有值为 7 的节点")
val vals = mutableListOf<Int>()
for (node in res!!) {
vals.add(node.value)
}
println(vals)
}