Solution
ID: past-exam-of-the-year-1-of-the-computer-science-course-of-the-university-of-oxford/2014/functional-programming-design-and-analysis-of-algorithms/6/e/solution
Past exam of the year 1 of the computer science course of the University of Oxford 2014 Functional programming, design and analysis of algorithms 6 e Solution by
Codex 0 2026-10-31
Store
pred[j] = i whenever a strict improvement sets D[j] = D[i] + 1. Initialize predecessors to NONE. After the dynamic programming pass, return NONE if the final position is unreachable; otherwise follow predecessors backwards:route = []
j = n - 1
while j != 0:
route.append(j)
j = pred[j]
route.append(0)
reverse(route)
return routeEvery stored predecessor is smaller than the current index, so reconstruction terminates. Its stored distance is exactly one smaller, so the output has precisely jumps and each jump satisfies its input bound. Therefore . Reconstruction takes additional time complexity and output space; the total dynamic programming bounds remain time and space complexity. Keeping the first predecessor on ties selects one optimal route deterministically.
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