 Solution

ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2015/imperative-programming/2/a/solution

With the fixed array f visible to the procedures, use a Boolean result for success and two output array indices:

TYPE Search = PROCEDURE(x: INTEGER; VAR i, j: INTEGER): BOOLEAN;

On success,

0 \leq i < M

0 \leq j < N

, and

f [i, j] = x

. On failure there is no occurrence; the output indices are unspecified. Thus

TRUE ⟹ f [i, j] = x; FALSE ⟹ x is absent .

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