Create post order examples in Scala

[vibhu172000]

DFS/BFS pre/post order examples in Scala

1. Issue Link:

2. Brief explanation of a change:

3. Will it break existing clients and code in production?

[amatiushkin]

@vibhu172000 Thank you for the contribution. How would you use traverser library (which this repo is about) to perform same task in scala?

[gkesler]

@vibhu172000 could you, please, put some description to your PR? tnx.

[vibhu172000]

DFS- Graph 9 7 0 1 1 2 1 3 2 3 3 4 6 7 6 8 Result Component 1 0 1 2 3 4 Component 2 5 Component 3 6 7 8 There are 3 connected components The important things worth mentioning here is the use of `forEach`with `it` variable and ranges from Kotlin helped me quite a lot. Use of `Pair` and variable like `tv.first` is also helpful. enum class Color { BLACK, WHITE } var vert: MutableList<Color> = mutableListOf() var adj: MutableList<MutableList<Pair<Int, Int>>> = mutableListOf() vert is a list of `Color` enum which is used track the visit status of each node. WHITE denotes if it’s unvisited while BLACK means it’s visited. adj maintains are graph in the form of adjacency list which `list of list of Pairs`. Pair contains two numbers of which first denotes the node and second denotes the weight associated with that edge which is in this case is `1`. the core DFS is very small fun dfs(u: Int) { vert[u] = Color.BLACK print(" $u") (0..adj[u].size-1).forEach { val tv = adj[u][it] if(vert[tv.first] == Color.WHITE) dfs(tv.first) } } BFS Graph 9 7 0 1 1 2 1 3 2 3 3 4 6 7 6 8 Result u: 0 and [Node(color=BLACK, distance=0, parent=-1), Node(color=BLACK, distance=1, parent=1), Node(color=BLACK, distance=2, parent=2), Node(color=BLACK, distance=2, parent=3), Node(color=BLACK, distance=3, parent=4)] u: 6 and [Node(color=BLACK, distance=0, parent=-1), Node(color=BLACK, distance=1, parent=7), Node(color=BLACK, distance=1, parent=8)] u: 5 and [Node(color=BLACK, distance=0, parent=-1)] use the following variables and enum class. enum class Color { BLACK, WHITE } var adj: MutableList<MutableList<Pair<Int, Int>>> = mutableListOf() We make use of a `data class Node` to keep track of color for visiting, distance and parent of the node while doing BFS.

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On Mon, Oct 19, 2020, 08:24 Alex Matiushkin ***@***.*** wrote: @vibhu172000 <https://github.com/vibhu172000> Thank you for the contribution. How would you use traverser library (which this repo is about) to perform same task in scala? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#20 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/APYLMOXEPECN5V24HREJFHLSLOS4TANCNFSM4SUAPXRQ> .

[gkesler]

@vibhu172000 thanks for sharing. I wonder how the mechanism you've described would improve traverser component?