Learn: Tree
What: nodes in a hierarchy. One root at the top, each node has children, nodes with no children are leaves.
Use it when: data is nested: folders, HTML, company org charts, menus, and database indexes.
Most tree problems are recursion: solve for the children, then combine.
```csharp
var root = new Tree(1, new Tree(2, null, null), new Tree(3, new Tree(4, null, null), null));
Console.WriteLine(Count(root));
static int Count(Tree? t) => t == null ? 0 : 1 + Count(t.Left) + Count(t.Right);
```
It prints 4: the number of nodes.
Read more: https://www.geeksforgeeks.org/dsa/tree-data-structure/
#tip · TIP-030
npub1u6…v0yg2
2026-10-26 10:37:49 UTC
Author Public Key
npub1u69qs4hfpkve0v0hy85s2fycjeqjm4ts8xdfs7ew3l270l87yfuspv0yg2Seen on
wss://relay.primal.netPublished at
2026-10-26 10:37:49 UTCEvent JSON
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"content": "Learn: Tree\n\nWhat: nodes in a hierarchy. One root at the top, each node has children, nodes with no children are leaves.\nUse it when: data is nested: folders, HTML, company org charts, menus, and database indexes.\nMost tree problems are recursion: solve for the children, then combine.\n\n```csharp\nvar root = new Tree(1, new Tree(2, null, null), new Tree(3, new Tree(4, null, null), null));\nConsole.WriteLine(Count(root));\n\nstatic int Count(Tree? t) =\u003e t == null ? 0 : 1 + Count(t.Left) + Count(t.Right);\n```\n\nIt prints 4: the number of nodes.\n\nRead more: https://www.geeksforgeeks.org/dsa/tree-data-structure/\n\n#tip · TIP-030",
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