How do I install the Data Structures skill?

Run npx skillmds@latest add markus41/data-structures in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

What does the Data Structures skill do?

Computer science data structure visualization in draw.io — arrays, linked lists, trees, graphs, hash tables, heaps, stacks, queues It is listed under Coding & Dev Tools on SkillMD.

Is Data Structures safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Data Structures?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Data Structures free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Data Structures?

markus41 (@markus41) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Data Structures by markus41 — Agent Skill

Name: Data Structures
Author: markus41

Data Structure Diagrams

Quick Reference

Structure	Best For	Complexity
Array	Sequential data, index access	Low
Linked List	Insertion/deletion demos	Low
Stack	LIFO operations, call stacks	Low
Queue	FIFO operations, BFS	Low
Binary Tree	Hierarchical data, BST	Medium
AVL / Red-Black Tree	Balanced search demos	Medium
B-Tree	Database index visualization	High
Heap	Priority queue, heapsort	Medium
Hash Table	Key-value mapping, collisions	Medium
Graph	Networks, relationships, paths	Medium-High
Trie	Prefix search, autocomplete	Medium

Shared Style Constants

Cell colors:
  Default:    fillColor=#DAE8FC;strokeColor=#6C8EBF;  (blue)
  Highlight:  fillColor=#D5E8D4;strokeColor=#82B366;  (green — active/found)
  Alert:      fillColor=#F8CECC;strokeColor=#B85450;  (red — removed/error)
  Visited:    fillColor=#FFF2CC;strokeColor=#D6B656;  (yellow — traversed)
  Empty:      fillColor=#F5F5F5;strokeColor=#CCCCCC;  (gray — null/empty)

Text:  fontColor=#333333;fontSize=14;fontFamily=Consolas;
Index: fontColor=#999999;fontSize=10;fontStyle=2;  (italic, small)
Arrow: strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;

Arrays

Linear Array

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Index labels -->
    <mxCell id="idx0" value="0" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#999999;fontSize=10;fontStyle=2;align=center;" vertex="1" parent="1">
      <mxGeometry x="40" y="20" width="60" height="20" as="geometry"/>
    </mxCell>
    <mxCell id="idx1" value="1" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#999999;fontSize=10;fontStyle=2;align=center;" vertex="1" parent="1">
      <mxGeometry x="100" y="20" width="60" height="20" as="geometry"/>
    </mxCell>
    <mxCell id="idx2" value="2" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#999999;fontSize=10;fontStyle=2;align=center;" vertex="1" parent="1">
      <mxGeometry x="160" y="20" width="60" height="20" as="geometry"/>
    </mxCell>
    <mxCell id="idx3" value="3" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#999999;fontSize=10;fontStyle=2;align=center;" vertex="1" parent="1">
      <mxGeometry x="220" y="20" width="60" height="20" as="geometry"/>
    </mxCell>
    <mxCell id="idx4" value="4" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#999999;fontSize=10;fontStyle=2;align=center;" vertex="1" parent="1">
      <mxGeometry x="280" y="20" width="60" height="20" as="geometry"/>
    </mxCell>
    <!-- Array cells -->
    <mxCell id="a0" value="42" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontColor=#333333;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="40" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="a1" value="17" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontColor=#333333;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="100" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="a2" value="93" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#D5E8D4;strokeColor=#82B366;fontColor=#333333;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="160" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="a3" value="8" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontColor=#333333;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="220" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="a4" value="51" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontColor=#333333;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="280" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <!-- Pointer arrow -->
    <mxCell id="ptr" value="current" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#B85450;fontSize=11;fontStyle=1;align=center;" vertex="1" parent="1">
      <mxGeometry x="160" y="90" width="60" height="20" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

2D Matrix

Use a grid of cells. Each row shares the same Y, each column the same X. Add row/column headers with index labels.

<!-- Row 0 -->
<mxCell id="m00" value="1" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="80" y="40" width="50" height="40" as="geometry"/>
</mxCell>
<mxCell id="m01" value="2" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="130" y="40" width="50" height="40" as="geometry"/>
</mxCell>
<mxCell id="m02" value="3" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="180" y="40" width="50" height="40" as="geometry"/>
</mxCell>
<!-- Row 1 -->
<mxCell id="m10" value="4" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="80" y="80" width="50" height="40" as="geometry"/>
</mxCell>

Linked Lists

Singly Linked List

Each node has a data cell and a pointer cell side by side:

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Node 1 -->
    <mxCell id="n1data" value="10" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="40" y="60" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="n1ptr" value="&#x2022;" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=18;" vertex="1" parent="1">
      <mxGeometry x="100" y="60" width="30" height="40" as="geometry"/>
    </mxCell>
    <!-- Node 2 -->
    <mxCell id="n2data" value="20" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="200" y="60" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="n2ptr" value="&#x2022;" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=18;" vertex="1" parent="1">
      <mxGeometry x="260" y="60" width="30" height="40" as="geometry"/>
    </mxCell>
    <!-- Node 3 (tail) -->
    <mxCell id="n3data" value="30" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="360" y="60" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="n3ptr" value="&#x2205;" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#F5F5F5;strokeColor=#CCCCCC;fontSize=14;" vertex="1" parent="1">
      <mxGeometry x="420" y="60" width="30" height="40" as="geometry"/>
    </mxCell>
    <!-- Arrows -->
    <mxCell id="e12" style="edgeStyle=entityRelationEdgeStyle;strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;" edge="1" source="n1ptr" target="n2data" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="e23" style="edgeStyle=entityRelationEdgeStyle;strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;" edge="1" source="n2ptr" target="n3data" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <!-- Head label -->
    <mxCell id="head" value="head" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#B85450;fontSize=11;fontStyle=1;align=center;" vertex="1" parent="1">
      <mxGeometry x="40" y="36" width="60" height="20" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Doubly Linked List

Same as above but add a second pointer cell on the left of each node, and backward arrows.

Stacks and Queues

Stack (LIFO)

Vertical arrangement, top item highlighted:

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <mxCell id="sLabel" value="&lt;b&gt;Stack&lt;/b&gt;" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#333333;fontSize=16;align=center;" vertex="1" parent="1">
      <mxGeometry x="60" y="10" width="80" height="24" as="geometry"/>
    </mxCell>
    <!-- Top (most recent push) -->
    <mxCell id="s3" value="&lt;b&gt;C&lt;/b&gt;  ← top" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#D5E8D4;strokeColor=#82B366;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="40" y="40" width="120" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="s2" value="B" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="40" y="80" width="120" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="s1" value="A" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="40" y="120" width="120" height="40" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Queue (FIFO)

Horizontal arrangement with front/rear labels:

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <mxCell id="front" value="front →" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#B85450;fontSize=11;fontStyle=1;align=right;" vertex="1" parent="1">
      <mxGeometry x="0" y="48" width="55" height="24" as="geometry"/>
    </mxCell>
    <mxCell id="q1" value="A" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#D5E8D4;strokeColor=#82B366;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="60" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="q2" value="B" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="120" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="q3" value="C" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="180" y="40" width="60" height="40" as="geometry"/>
    </mxCell>
    <mxCell id="rear" value="← rear" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#B85450;fontSize=11;fontStyle=1;align=left;" vertex="1" parent="1">
      <mxGeometry x="245" y="48" width="55" height="24" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Binary Trees

Binary Search Tree

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Root -->
    <mxCell id="n8" value="8" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="260" y="40" width="50" height="50" as="geometry"/>
    </mxCell>
    <!-- Level 1 -->
    <mxCell id="n3" value="3" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="140" y="130" width="50" height="50" as="geometry"/>
    </mxCell>
    <mxCell id="n10" value="10" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="380" y="130" width="50" height="50" as="geometry"/>
    </mxCell>
    <!-- Level 2 -->
    <mxCell id="n1" value="1" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="80" y="220" width="50" height="50" as="geometry"/>
    </mxCell>
    <mxCell id="n6" value="6" style="ellipse;whiteSpace=wrap;html=1;fillColor=#D5E8D4;strokeColor=#82B366;fontSize=16;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="200" y="220" width="50" height="50" as="geometry"/>
    </mxCell>
    <mxCell id="n14" value="14" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="440" y="220" width="50" height="50" as="geometry"/>
    </mxCell>
    <!-- Edges -->
    <mxCell id="e1" style="strokeColor=#666666;strokeWidth=2;endArrow=none;" edge="1" source="n8" target="n3" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="e2" style="strokeColor=#666666;strokeWidth=2;endArrow=none;" edge="1" source="n8" target="n10" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="e3" style="strokeColor=#666666;strokeWidth=2;endArrow=none;" edge="1" source="n3" target="n1" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="e4" style="strokeColor=#666666;strokeWidth=2;endArrow=none;" edge="1" source="n3" target="n6" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="e5" style="strokeColor=#666666;strokeWidth=2;endArrow=none;" edge="1" source="n10" target="n14" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Node Style Variants

Type	Style	Use
Default node	`ellipse;fillColor=#DAE8FC;strokeColor=#6C8EBF;`	Unvisited
Current / found	`ellipse;fillColor=#D5E8D4;strokeColor=#82B366;`	Highlight during traversal
Removed	`ellipse;fillColor=#F8CECC;strokeColor=#B85450;dashed=1;`	Deleted node
Null leaf	`ellipse;fillColor=#F5F5F5;strokeColor=#CCCCCC;fontColor=#CCCCCC;`	NIL sentinel

AVL Tree Annotations

Add balance factor as a superscript label above each node:

<mxCell id="bf" value="bf=+1" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#999999;fontSize=9;align=center;" vertex="1" parent="1">
  <mxGeometry x="250" y="24" width="70" height="16" as="geometry"/>
</mxCell>

Heaps

Min-Heap (Array-backed tree)

Show both the tree view and the underlying array. Use the same node IDs so the relationship is clear.

Tree layout is identical to BST above. Below the tree, add the array view:

<!-- Array representation -->
<mxCell id="arrLabel" value="&lt;b&gt;Array:&lt;/b&gt;" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#333;fontSize=12;align=right;" vertex="1" parent="1">
  <mxGeometry x="0" y="320" width="60" height="30" as="geometry"/>
</mxCell>
<mxCell id="h0" value="1" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#D5E8D4;strokeColor=#82B366;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="70" y="320" width="45" height="30" as="geometry"/>
</mxCell>
<mxCell id="h1" value="3" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="115" y="320" width="45" height="30" as="geometry"/>
</mxCell>
<mxCell id="h2" value="5" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=13;fontFamily=Consolas;" vertex="1" parent="1">
  <mxGeometry x="160" y="320" width="45" height="30" as="geometry"/>
</mxCell>

Hash Tables

Separate Chaining

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <mxCell id="title" value="&lt;b&gt;Hash Table (size=5, separate chaining)&lt;/b&gt;" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#333;fontSize=14;align=left;" vertex="1" parent="1">
      <mxGeometry x="20" y="10" width="400" height="24" as="geometry"/>
    </mxCell>
    <!-- Bucket 0 -->
    <mxCell id="b0" value="[0]" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#E6E6E6;strokeColor=#999999;fontSize=13;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="20" y="50" width="60" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="b0n1" value="&quot;apple&quot;" style="rounded=1;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=12;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="120" y="50" width="80" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="b0e1" style="strokeColor=#666;strokeWidth=1;endArrow=block;endFill=1;" edge="1" source="b0" target="b0n1" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <!-- Bucket 1 (empty) -->
    <mxCell id="b1" value="[1]" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#E6E6E6;strokeColor=#999999;fontSize=13;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="20" y="96" width="60" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="b1null" value="null" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#CCCCCC;fontSize=11;fontFamily=Consolas;fontStyle=2;" vertex="1" parent="1">
      <mxGeometry x="120" y="104" width="40" height="20" as="geometry"/>
    </mxCell>
    <!-- Bucket 2 (chain of 2) -->
    <mxCell id="b2" value="[2]" style="rounded=0;whiteSpace=wrap;html=1;fillColor=#E6E6E6;strokeColor=#999999;fontSize=13;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="20" y="142" width="60" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="b2n1" value="&quot;banana&quot;" style="rounded=1;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=12;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="120" y="142" width="80" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="b2n2" value="&quot;grape&quot;" style="rounded=1;whiteSpace=wrap;html=1;fillColor=#FFF2CC;strokeColor=#D6B656;fontSize=12;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="240" y="142" width="80" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="b2e1" style="strokeColor=#666;strokeWidth=1;endArrow=block;endFill=1;" edge="1" source="b2" target="b2n1" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="b2e2" style="strokeColor=#666;strokeWidth=1;endArrow=block;endFill=1;" edge="1" source="b2n1" target="b2n2" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Open Addressing (Linear Probing)

Use a single row of cells (like an array) with color coding:

Color	Meaning
Blue (`#DAE8FC`)	Occupied — hashed to this index
Yellow (`#FFF2CC`)	Occupied — probed to this index (collision)
Gray (`#F5F5F5`)	Empty slot
Red (`#F8CECC`)	Tombstone (deleted)

Graphs

Directed Graph (Adjacency Visualization)

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Vertices -->
    <mxCell id="vA" value="A" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="200" y="40" width="50" height="50" as="geometry"/>
    </mxCell>
    <mxCell id="vB" value="B" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="80" y="160" width="50" height="50" as="geometry"/>
    </mxCell>
    <mxCell id="vC" value="C" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="320" y="160" width="50" height="50" as="geometry"/>
    </mxCell>
    <mxCell id="vD" value="D" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=16;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="200" y="280" width="50" height="50" as="geometry"/>
    </mxCell>
    <!-- Directed edges with weights -->
    <mxCell id="eAB" value="4" style="strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;fontColor=#B85450;fontSize=11;fontStyle=1;" edge="1" source="vA" target="vB" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="eAC" value="2" style="strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;fontColor=#B85450;fontSize=11;fontStyle=1;" edge="1" source="vA" target="vC" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="eBD" value="3" style="strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;fontColor=#B85450;fontSize=11;fontStyle=1;" edge="1" source="vB" target="vD" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="eCD" value="1" style="strokeColor=#666666;strokeWidth=2;endArrow=block;endFill=1;fontColor=#B85450;fontSize=11;fontStyle=1;" edge="1" source="vC" target="vD" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Undirected Graph

Same as directed but use endArrow=none;startArrow=none; on edges.

Graph Traversal Coloring

Show BFS/DFS state with node colors:

State	Fill	Meaning
Unvisited	`#DAE8FC` (blue)	Not yet discovered
In queue/stack	`#FFF2CC` (yellow)	Discovered, not processed
Processing	`#D5E8D4` (green)	Currently visiting
Completed	`#E6E6E6` (gray)	Fully processed

Tries

Prefix Trie

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Root -->
    <mxCell id="root" value="" style="ellipse;whiteSpace=wrap;html=1;fillColor=#E6E6E6;strokeColor=#999;fontSize=12;" vertex="1" parent="1">
      <mxGeometry x="200" y="20" width="30" height="30" as="geometry"/>
    </mxCell>
    <!-- Level 1 -->
    <mxCell id="c" value="c" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="120" y="80" width="36" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="d" value="d" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="280" y="80" width="36" height="36" as="geometry"/>
    </mxCell>
    <!-- Level 2 -->
    <mxCell id="ca" value="a" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="80" y="150" width="36" height="36" as="geometry"/>
    </mxCell>
    <mxCell id="co" value="o" style="ellipse;whiteSpace=wrap;html=1;fillColor=#DAE8FC;strokeColor=#6C8EBF;fontSize=14;fontFamily=Consolas;" vertex="1" parent="1">
      <mxGeometry x="160" y="150" width="36" height="36" as="geometry"/>
    </mxCell>
    <!-- Level 3 — word end nodes highlighted -->
    <mxCell id="cat" value="t" style="ellipse;whiteSpace=wrap;html=1;fillColor=#D5E8D4;strokeColor=#82B366;fontSize=14;fontFamily=Consolas;fontStyle=1;" vertex="1" parent="1">
      <mxGeometry x="80" y="220" width="36" height="36" as="geometry"/>
    </mxCell>
    <!-- "cat" label -->
    <mxCell id="catLabel" value="&quot;cat&quot;" style="text;html=1;fillColor=none;strokeColor=none;fontColor=#82B366;fontSize=10;align=center;" vertex="1" parent="1">
      <mxGeometry x="68" y="258" width="60" height="16" as="geometry"/>
    </mxCell>
    <!-- Edges -->
    <mxCell id="erc" style="strokeColor=#666;strokeWidth=1;endArrow=none;" edge="1" source="root" target="c" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="erd" style="strokeColor=#666;strokeWidth=1;endArrow=none;" edge="1" source="root" target="d" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="eca" style="strokeColor=#666;strokeWidth=1;endArrow=none;" edge="1" source="c" target="ca" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="eco" style="strokeColor=#666;strokeWidth=1;endArrow=none;" edge="1" source="c" target="co" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
    <mxCell id="ecat" style="strokeColor=#666;strokeWidth=1;endArrow=none;" edge="1" source="ca" target="cat" parent="1">
      <mxGeometry relative="1" as="geometry"/>
    </mxCell>
  </root>
</mxGraphModel>

Green nodes (#D5E8D4) mark word endings (isEnd=true).

Layout Tips

Consistent spacing — Use 8px grid; tree levels at 80-100px vertical intervals
Color meaning — Pick a legend and stick to it (blue=default, green=active, red=removed, yellow=visited)
Monospace font — Always fontFamily=Consolas; for data values
Index labels — Use small italic gray text above/below cells
Pointer arrows — strokeWidth=2;endArrow=block;endFill=1; for linked structures
Animation frames — Use draw.io pages for step-by-step algorithm visualization (page 1: initial, page 2: step 1, etc.)
Null sentinels — Gray fill, dashed stroke, null or ∅ text

Data Structures

File contents

Data Structure Diagrams

Quick Reference

Shared Style Constants

Arrays

Linear Array

2D Matrix

Linked Lists

Singly Linked List

Doubly Linked List

Stacks and Queues

Stack (LIFO)

Queue (FIFO)

Binary Trees

Binary Search Tree

Node Style Variants

AVL Tree Annotations

Heaps

Min-Heap (Array-backed tree)

Hash Tables

Separate Chaining

Open Addressing (Linear Probing)

Graphs

Directed Graph (Adjacency Visualization)

Undirected Graph

Graph Traversal Coloring

Tries

Prefix Trie

Layout Tips

Frequently asked questions

Data Structures

File contents

Data Structure Diagrams

Quick Reference

Shared Style Constants

Arrays

Linear Array

2D Matrix

Linked Lists

Singly Linked List

Doubly Linked List

Stacks and Queues

Stack (LIFO)

Queue (FIFO)

Binary Trees

Binary Search Tree

Node Style Variants

AVL Tree Annotations

Heaps

Min-Heap (Array-backed tree)

Hash Tables

Separate Chaining

Open Addressing (Linear Probing)

Graphs

Directed Graph (Adjacency Visualization)

Undirected Graph

Graph Traversal Coloring

Tries

Prefix Trie

Layout Tips

Related skills

Frequently asked questions

How do I install the Data Structures skill?

What does the Data Structures skill do?

Is Data Structures safe to use?

Which AI agents work with Data Structures?

Is Data Structures free to use?

Who published Data Structures?