ITPEC FE Morning April 2018 Question 6
Topic: Algorithm and ProgrammingAlso asked in April 2022
There is a two-dimensional integer array A whose (i, j)-th element A[i, j] is 2 × i + j. What is the value of the element A[A[1, 1] × 2, A[2, 2] + 1]?
Explanation
19 — work out the inner elements first, then use them as the indices of the outer element.
- •A[1, 1] = 2 × 1 + 1 = 3
- •A[2, 2] = 2 × 2 + 2 = 6
- •Row index: A[1, 1] × 2 = 3 × 2 = 6
- •Column index: A[2, 2] + 1 = 6 + 1 = 7
- •A[6, 7] = 2 × 6 + 7 = 19
Answer (d)
Why not others:
- •(a) 12 — only 2 × i = 2 × 6; the column index j = 7 is never added
- •(b) 13 — 6 + 7, adding the two indices without doubling the row index
- •(c) 18 — A[6, 6] = 12 + 6; the + 1 in the column index is left out
Key rule: Evaluate nested subscripts from the inside out, and apply the element formula only after both indices are known.
Algorithm and Programming · AI-written, may contain errors
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