Merge Intervals

flowchart TD
    S["<b>i · sort</b><br/>intervals.sort(key=x[0])"]
      --> I["<b>ii · init</b><br/>merged = [intervals[0]]"]
      --> L{"<b>iii · next interval?</b><br/>for s, e in intervals[1:]"}
    L -->|"yes"| C{"<b>iv · overlap?</b><br/>s ≤ merged[-1][1]?"}
    C -->|"yes"| M["<b>v · extend</b><br/>merged[-1][1] = max(merged[-1][1], e)"]
    C -->|"no"| N["<b>vi · new bucket</b><br/>merged.append([s, e])"]
    M --> L
    N --> L
    L -->|"done"| R["<b>return</b> merged"]
 
    classDef start fill:#f5efe1,stroke:#6a8a4f,stroke-width:2px,color:#1a1915;
    classDef decision fill:#fdecd3,stroke:#c2410c,stroke-width:2px,color:#1a1915;
    classDef action fill:#e7efd9,stroke:#587640,stroke-width:2px,color:#1a1915;
    class S,I start
    class L,C decision
    class M,N,R action