ITPEC FE Subject B April 2025 Question 12

Hamming distance counts positions where two equal-length arrays differ

The function hammingDistance takes two character arrays s1 and s2. If their lengths differ, it returns -1. Otherwise, it iterates through each index and counts how many positions have different values.

The missing condition is s1[i] ≠ s2[i] — the loop variable is i, and we need to compare elements at the same index and increment cnt when they differ.

Why not others:
- s1[i] = s2[i] (g) — would count matching positions, not differences
- Options using cnt as index (a–d) — cnt is the counter, not the loop variable; using it as an index would compare wrong positions
- s1[i] = s2[cnt] (e) or s1[i] ≠ s2[cnt] (f) — mixes loop index with counter, comparing mismatched positions

Key rule: In Hamming distance, compare elements at the same index using the loop variable, and count where they differ (≠).

AI-generated — may contain errors