Chapter 7: Problem 22

If a sequential search is performed on an array, and it is known that some items are searched for more frequently than others, how can the contents of the array be reordered to improve the average performance of the search?

Short Answer

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Answer: The average performance of a sequential search can be improved by reordering the array based on the search frequency of its elements. Start by gathering frequency data about how often each element is searched, and then sort the array so that elements with higher search frequencies are placed before elements with lower search frequencies. After performing the sequential search on the reordered array, compare its performance to the original unsorted array to verify the improvement. Continuously update the frequency data and reorder the array as needed to maintain optimal performance.

Step by step solution

Obtain Frequency Data

First, gather data on which elements of the array are searched for more frequently. This can be achieved by counting the number of times each item is searched for during a specific period or using historical data if available.

Sort the Elements Based on Frequency

Next, sort the elements in the array according to their frequency, in descending order. This means that the element with the highest search frequency should be placed at the beginning of the array (index 0), followed by the one with the second-highest frequency, and so on.

Perform the Sequential Search on the Reordered Array

Now that the array is reordered to have the most frequently searched items earlier in the array, perform the sequential search on the modified array as usual. This means starting from the first item (highest search frequency) and scanning through the array one item at a time until the desired item is found or the end of the array is reached.

Compare Performance

To verify the improvement in average performance of the modified search, compare the search time or number of comparisons for the original unsorted array and the reordered array, given the search frequency data. The reordered array should have a shorter average search time or fewer average comparisons for most searched elements, leading to better overall performance.

Update Frequency Data and Reorder

Continue to update the frequency data over time, as users search for items. Periodically reorder the array based on the updated frequency data to maintain an optimal arrangement for the sequential search and keep improving the average performance of the search.

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If a sequential search is performed on an array, and it is known that some items are searched for more frequently than others, how can the contents of the array be reordered to improve the average performance of the search?

Short Answer

Step by step solution

Obtain Frequency Data

Sort the Elements Based on Frequency

Perform the Sequential Search on the Reordered Array

Compare Performance

Update Frequency Data and Reorder

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