Python implementation of the Selection Sort algorithm

Data Structure Sorting (Article) Sorting (Program)

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Given Input: 

Original array: [64, 25, 12, 22, 11]

Expected Output: 

Sorted array: [11, 12, 22, 25, 64]

Program:

<span class="com"># Selection Sort in Python</span><span class="pln">

</span><span class="kwd">def</span><span class="pln"> selection_sort</span><span class="pun">(</span><span class="pln">arr</span><span class="pun">):</span><span class="pln">
    </span><span class="com"># Traverse through all array elements</span><span class="pln">
    </span><span class="kwd">for</span><span class="pln"> i </span><span class="kwd">in</span><span class="pln"> range</span><span class="pun">(</span><span class="pln">len</span><span class="pun">(</span><span class="pln">arr</span><span class="pun">)):</span><span class="pln">
        </span><span class="com"># Find the minimum element in the unsorted portion of the array</span><span class="pln">
        min_idx </span><span class="pun">=</span><span class="pln"> i
        </span><span class="kwd">for</span><span class="pln"> j </span><span class="kwd">in</span><span class="pln"> range</span><span class="pun">(</span><span class="pln">i</span><span class="pun">+</span><span class="lit">1</span><span class="pun">,</span><span class="pln"> len</span><span class="pun">(</span><span class="pln">arr</span><span class="pun">)):</span><span class="pln">
            </span><span class="kwd">if</span><span class="pln"> arr</span><span class="pun">[</span><span class="pln">j</span><span class="pun">]</span><span class="pln"> </span><span class="pun">&lt;</span><span class="pln"> arr</span><span class="pun">[</span><span class="pln">min_idx</span><span class="pun">]:</span><span class="pln">
                min_idx </span><span class="pun">=</span><span class="pln"> j

        </span><span class="com"># Swap the found minimum element with the first element of the unsorted portion</span><span class="pln">
        arr</span><span class="pun">[</span><span class="pln">i</span><span class="pun">],</span><span class="pln"> arr</span><span class="pun">[</span><span class="pln">min_idx</span><span class="pun">]</span><span class="pln"> </span><span class="pun">=</span><span class="pln"> arr</span><span class="pun">[</span><span class="pln">min_idx</span><span class="pun">],</span><span class="pln"> arr</span><span class="pun">[</span><span class="pln">i</span><span class="pun">]</span><span class="pln">

</span><span class="com"># Example usage</span><span class="pln">
arr </span><span class="pun">=</span><span class="pln"> </span><span class="pun">[</span><span class="lit">64</span><span class="pun">,</span><span class="pln"> </span><span class="lit">25</span><span class="pun">,</span><span class="pln"> </span><span class="lit">12</span><span class="pun">,</span><span class="pln"> </span><span class="lit">22</span><span class="pun">,</span><span class="pln"> </span><span class="lit">11</span><span class="pun">]</span><span class="pln">
</span><span class="kwd">print</span><span class="pun">(</span><span class="str">"Original array:"</span><span class="pun">,</span><span class="pln"> arr</span><span class="pun">)</span><span class="pln">

selection_sort</span><span class="pun">(</span><span class="pln">arr</span><span class="pun">)</span><span class="pln">

</span><span class="kwd">print</span><span class="pun">(</span><span class="str">"Sorted array:"</span><span class="pun">,</span><span class="pln"> arr</span><span class="pun">)</span>

Output:

Original array: [64, 25, 12, 22, 11]
Sorted array: [11, 12, 22, 25, 64]

Explanation:

  • Outer Loop: Iterates over each element in the array.
  • Inner Loop: Finds the minimum element from the unsorted part of the array.
  • Swap: Swaps the minimum element with the first unsorted element.
  • Sorted Output: After the loops complete, the array is sorted in ascending order.

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