A-LevelComputer ScienceSystem software9618/21 · Oct/Nov 2023 · Q75 Marks

7 An algorithm is represented by a state-transition diagram. The table shows the inputs, outputs and states for the algorithm: Current state | Input | Output | Next state --------------|-------|--------|----------- S1 | A1 | X1 | S2 S2 | A3 | none | S1 S2 | A2 | X4 | S5 S5 | A1 | X1 | S5 S5 | A4 | X2 | S2 S5 | A3 | none | S3 S1 | A9 | X9 | S3 S3 | A9 | X9 | S4 Complete the state-transition diagram to represent the information given in the table. A1|X1 START S1 A3

(a)Complete the state-transition diagram to represent the information given in the table.[5]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2023). The mark or mark type is shown in brackets.

[1] S2 labelled (with a circle)
[1] S3, S4, and S5 added (as circles)
[1] Transition from S1 to S3: A9|X9
[1] All three transitions between S2 and S5: S2 to S5 (A2|X4), S5 to S5 (A1|X1), S5 to S2 (A4|X2)
[1] Transition from S5 to S3 (A3|none) AND from S3 to S4 (A9|X9)

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