1. 将该流程图转化为流图如下:
```
Start
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v
A: x = 0
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B: y = 0
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C: z = 0
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D: read a
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E: if a > 0 then F else G
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F: x = x + 1
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H: y = y + 1
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I: z = z + 1
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J: read a
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K: if a > 0 then L else M
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L: x = x + 1
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N: y = y + 1
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O: z = z + 1
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M: print x, y, z
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End
```
2. 确定该图的基本路径集合:
- 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> 11 -> 12 -> 13 -> 14 -> 15 -> 16 -> 17 -> 18
- 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> 11 -> 14 -> 15 -> 16 -> 17 -> 18
- 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> 11 -> 12 -> 13 -> 14 -> 15 -> 16 -> 17 -> 18
- 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> 11 -> 14 -> 15 -> 16 -> 17 -> 18
3. 根据基本路径集合设计测试用例:
- 对于第一条基本路径,输入 a = 1,期望输出 x=1, y=1, z=1。
- 对于第二条基本路径,输入 a = -1,期望输出 x=0, y=0, z=1。
- 对于第三条基本路径,输入