diffs to store the indices where s1 and s2 differ.diffs is odd, return -1 as it is impossible to make the strings equal.dp_i_plus_two, dp_i_plus_one, and dp_i to keep track of the costs.diffs in reverse order, calculating the minimum cost for each index.idx, calculate dp_i as the minimum of dp_i_plus_one + x / 2 and dp_i_plus_two + diffs[idx + 1] - diffs[idx].dp_i_plus_two and dp_i_plus_one for the next iteration.dp_i after the loop.