Efficiency in the table is being measured in big-oh. Actual execution times and memory usage would also be informative as big-oh doesn't tell the whole story...

Could it be some text got lost under the heading "On to Hashing"?

After the sentence "So to read or to write to any element in our new array based on the country code to locate the structure we have lost efficiency from our original approach of directly accessing memory locations." it makes a jump that doesn't quite flow correctly.