语法详见:https://mermaid.js.org/syntax/flowchart.html
| 语法 | 效果 |
|------------------|-------------|
| `A-->B` | 实线箭头 |
| `A-.->B` | 虚线箭头 |
| `A==>B` | 粗线箭头 |
| `A-- text -->B` | 带标签的箭头 |
flowchart TD
A[Start] --> B{Is it?}
B -->|Yes| C[OK]
C --> D[Rethink]
D --> B
B ---->|No| E[End]
flowchart TD A[Start] --> B{Is it?} B -->|Yes| C[OK] C --> D[Rethink] D --> B B ---->|No| E[End]