// Diagram 3: Complexity Comparison — stack.contains(n) vs n.active
// Shows operation count growth as graph size V increases.
// Defective: V*(V+1)/2 comparisons for a path graph with back edge.
// Fixed: 1 comparison per edge regardless of stack depth.
//
// Render: dot -Tsvg 0001-stack-scan.dot -o 0001-stack-scan.svg

digraph complexity_comparison {
    graph [
        label="Stack Membership Check: O(V²) Defect vs O(1) Fix\nComparisons required when back edge is reached on a path graph of V nodes"
        labelloc=t
        fontsize=13
        fontname="monospace"
        bgcolor="#f8f8f8"
        pad=0.6
    ]
    node [fontname="monospace" fontsize=10]
    edge [fontname="monospace" fontsize=9]

    // ── Defective: stack.contains(n) ────────────────────────────────────────
    subgraph cluster_defect {
        label="DEFECTIVE:  stack.contains(n)  —  GraphUtils.java:186"
        style=filled fillcolor="#fff0f0" color="#cc0000" penwidth=2
        fontcolor="#cc0000"

        d_v5  [label="V=5\n15 comparisons"   shape=rect style=filled fillcolor="#ff9999" height=0.6 width=1.4]
        d_v10 [label="V=10\n55 comparisons"  shape=rect style=filled fillcolor="#ff6666" height=1.0 width=1.4]
        d_v50 [label="V=50\n1275 comparisons" shape=rect style=filled fillcolor="#ff3333" height=2.0 width=1.4]
        d_v100[label="V=100\n5050 comparisons" shape=rect style=filled fillcolor="#cc0000" fontcolor=white height=3.0 width=1.4]

        d_v5 -> d_v10 -> d_v50 -> d_v100 [style=invis]

        d_label [label="O(V²)\ngrowth" shape=none fontcolor="#cc0000" fontsize=12]
    }

    // ── Fixed: n.active ─────────────────────────────────────────────────────
    subgraph cluster_fix {
        label="FIXED:  n.active  —  O(1) boolean read"
        style=filled fillcolor="#f0fff0" color="#006600" penwidth=2
        fontcolor="#006600"

        f_v5  [label="V=5\n1 comparison"   shape=rect style=filled fillcolor="#99ff99" height=0.25 width=1.4]
        f_v10 [label="V=10\n1 comparison"  shape=rect style=filled fillcolor="#99ff99" height=0.25 width=1.4]
        f_v50 [label="V=50\n1 comparison"  shape=rect style=filled fillcolor="#99ff99" height=0.25 width=1.4]
        f_v100[label="V=100\n1 comparison" shape=rect style=filled fillcolor="#99ff99" height=0.25 width=1.4]

        f_v5 -> f_v10 -> f_v50 -> f_v100 [style=invis]

        f_label [label="O(1)\nper edge" shape=none fontcolor="#006600" fontsize=12]
    }

    // ── Source location ──────────────────────────────────────────────────────
    src_defect [
        label="GraphUtils.java:186\n} else if (stack.contains(n)) {\n    // ListBuffer linear scan"
        shape=box style="filled,rounded" fillcolor="#ffeeee"
        fontcolor="#cc0000" penwidth=2
    ]
    src_fix [
        label="GraphUtils.java:186  (patched)\n} else if (n.active) {\n    // TarjanNode.active field — O(1)"
        shape=box style="filled,rounded" fillcolor="#eeffee"
        fontcolor="#006600" penwidth=2
    ]

    src_defect -> d_v5  [label="drives" color="#cc0000" style=dashed]
    src_fix    -> f_v5  [label="drives" color="#006600" style=dashed]

    // ── Where Tarjan fires ───────────────────────────────────────────────────
    callers [
        label="Call sites:\nInfer.java:1908  (type inference — every call site with unresolved vars)\nDeferredAttr.java:675  (stuck expression resolution — every lambda/method-ref)"
        shape=box style=filled fillcolor="#e8e8ff"
    ]
    callers -> src_defect [style=dotted]
    callers -> src_fix    [style=dotted]
}