106 lines
4.6 KiB
HTML
106 lines
4.6 KiB
HTML
<!doctype html>
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<title>Week 4: Programming Assignments (8 points)</title>
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<meta charset="utf-8">
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</head>
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<body>
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<div>
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<h4><strong>Programming Assignments: Hashing</strong></h4>
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</div>
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<div>Both assignments are related to fixed sized hash tables. The hash tables store string (str) values.
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The hash value (slot) is calculated with the following hash function for strings:</div>
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<p></p>
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<pre>procedure hash(data):
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sum = 0
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for i = 0 to N-1 do
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sum += ascii(data[i])
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return sum % X
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</pre>
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<p></p>
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<div>where N is the length of the string (data), <span style="color: rgb(33, 37, 41); font-family: SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; font-size: 14px;">% </span>is the symbol for the mod operation and <span style="color: rgb(33, 37, 41); font-family: SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace; font-size: 14px;">X </span>is a parameter of the hash table. The ascii value of a character can be calculated with the function <strong><a href="https://www.w3schools.com/python/ref_func_ord.asp">ord</a></strong> in Python.</div>
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<br>
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<br>
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<div>
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<h4><strong>Assignment 4.1: Linear Probing </strong>(4 points)</h4>
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</div>
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<div>Implement a fixed sized hash table in Python that uses <u>linear probing</u> for collision resolution.
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Create a class <strong>HashLinear</strong> which has the table size \(M\) as a input value when a object is created. The class has following methods:</div>
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<ul>
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<ul>
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<li><strong>insert(data: str)</strong>: inserts new data into the hash table, no duplicates</li>
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<li><strong>delete(data: str)</strong>: removes data from the hash table</li>
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<li><strong>print()</strong>: prints the content of the hash table (the data string in each slot separated with a space; skip empty slots; see the example below)</li>
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</ul>
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</ul>
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<div>For hashing use \(X = M\).</div>
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<p></p>
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<div>A code template with an example program (the hash table has the size of \(M=8\)): </div>
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<p></p>
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<div style="border:2px solid black">
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<pre>class HashLinear:
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# TODO
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if __name__ == "__main__":
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table = HashLinear(8)
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table.insert("BM40A1500")
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table.insert("fOo")
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table.insert("123")
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table.insert("Bar1")
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table.insert("10aaaa1")
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table.insert("BM40A1500")
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table.print() # 10aaaa1 BM40A1500 fOo 123 Bar1
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table.delete("fOo")
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table.delete("Some arbitary string which is not in the table")
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table.delete("123")
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table.print() # 10aaaa1 BM40A1500 Bar1
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</pre>
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</div>
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<div><br></div><div>Submit your solution in CodeGrade as <strong>hashlinear.py</strong>.</div>
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<br>
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<br>
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<div>
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<h4><strong>Assignment 4.1: Bucket Hashing </strong>(4 points)</h4>
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</div>
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<div>Implement a fixed sized hash table in Python that uses <u>bucket hashing</u> for collision resolution.
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Create a class <strong>HashBucket</strong> which has the table size \(M\) and number of equal sized buckets \(B\) as the input values when a object is created.
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The hash table has a overflow array of size \(M\). The class has the following methods:</div>
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<ul>
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<ul>
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<li><strong>insert(data)</strong>: inserts new data in the hash table, no duplicates</li>
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<li><strong>delete(data)</strong>: removes data from the hash table</li>
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<li><strong>print()</strong>: prints the content of the hash table and the overflow array (the data string in each slot followed by the data in the overflow array; slots separated with a space and empty slots skipped; see the example below)</li>
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</ul>
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</ul>
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<div>For hashing use \(X = B\). Filling the buckets starts from the top and overflow values are appended to the end of the overflow array. </div>
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<p></p>
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<div>A code template with an example program (the hash table has the size of \(M=8\) and has \(B=4\) buckets):<br></div>
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<p></p>
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<div style="border:2px solid black"><pre>class HashBucket:
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# TODO
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if __name__ == "__main__":
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table = HashBucket(8, 4)
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table.insert("BM40A1500")
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table.insert("fOo")
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table.insert("123")
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table.insert("Bar1")
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table.insert("10aaaa1")
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table.insert("BM40A1500")
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table.print() # fOo BM40A1500 123 Bar1 10aaaa1
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table.delete("fOo")
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table.delete("Some arbitary string which is not in the table")
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table.delete("123")
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table.print() # BM40A1500 Bar1 10aaaa1
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</pre>
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</div>
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<div><br></div><div>Submit your solution in CodeGrade as <strong>hashbucket.py</strong>.</div>
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</body>
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</html> |