Easy to understand - PostOrder/DFS traversal With TestCases
https://github.com/Freeze777/SDE-Interviewer-Notes/blob/main/LeetCodeKotlin/src/main/kotlin/leetcode/medium/graph/MinTimeCollectApplesTree.kt
https://github.com/Freeze777/SDE-Interviewer-Notes/blob/main/LeetCodeKotlin/src/main/kotlin/leetcode/medium/graph/MinTimeCollectApplesTree.kt
['Depth-First Search', 'Kotlin']