【scala】含有list子集的递归方法记录层数深度

样例使用scala语言编写。
特点：
RecursiveData对象中包含一个成员child含有多个RecursiveData子对象。

思路：
递归方法中传入一个：int作为parent的深度，传入一个set记录所以深度集合。

同一深度int+1不会影响相同深度的结果，set又可以将统一深度层去重。

容易犯错误：使用单独对象记录，应为是递归是树形结构，随着层数和枝叶增加，会多计算，如recWrong方法就是错误典型。

import org.scalatest.funsuite.AnyFunSuiteimport java.util.concurrent.atomic.AtomicInteger
import scala.collection.mutablecase class RecursiveData(name: String, child: List[RecursiveData])class RecursiveTest extends AnyFunSuite {val r41 = RecursiveData("41", List.empty)val r42 = RecursiveData("42", List.empty)val r43 = RecursiveData("43", List.empty)val r44 = RecursiveData("44", List.empty)val r31 = RecursiveData("31", List(r41, r42))val r32 = RecursiveData("32", List(r43, r44))val r33 = RecursiveData("33", List.empty)val r34 = RecursiveData("34", List.empty)val r35 = RecursiveData("35", List.empty)val r36 = RecursiveData("36", List.empty)val r37 = RecursiveData("37", List.empty)val r21 = RecursiveData("21", List(r31, r32, r33))val r22 = RecursiveData("22", List(r34, r35))val r23 = RecursiveData("23", List(r36, r37))val r11 = RecursiveData("11", List(r21, r22, r23))def rec(data: RecursiveData, parentDepth: Int, depths: mutable.Set[Integer]): Unit = {val currDepth = parentDepth + 1depths.add(currDepth)data.child.foreach(c => {rec(c, currDepth, depths)})}test("test-recursive-right") {val depths: mutable.Set[Integer] = mutable.Set.emptyrec(r11, 0, depths)println(s"current depths:${depths},and max depths:${depths.max}")// current depths:Set(1, 2, 3, 4),and max depths:4}def recWrong(data: RecursiveData, depth: AtomicInteger): Unit = {data.child.foreach(c => {recWrong(c, depth)})if (data.child.nonEmpty) {// 错误思路: 每次增加减去相应的子成员增加量depth.set(depth.get() - (data.child.size - 1))}depth.getAndIncrement()}test("test-recursive-wrong") {val depth: AtomicInteger = new AtomicIntegerrecWrong(r11, depth)println(depth)// 7}
}