ITPEC IP October 2025 Question 8
ITPEC IP October 2025 — Question 8 of 100
Start at index 2 and add the preceding prefix sum — use arr[i - 1] to combine the current input with the sum immediately before it.
The program initializes arr[1] = inputarr[1], so the loop must begin at index 2. For every later index i, the sum through i equals the current value inputarr[i] plus the already calculated sum through i - 1, namely arr[i - 1].
Answer (d)
Why not others:
- (a) and (b) start at 1 and either access beyond the current prefix or use arr[0], outside the 1-based array
- (c) starts correctly but accesses arr[i + 1], which is uncalculated and exceeds the array at i = n
Key rule: A prefix-sum recurrence is prefix[i] = prefix[i - 1] + value[i] after initializing the first element.
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