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    <h1 class="text-center">Huffman Coding</h1>
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    <h3>What are Huffman Codes?</h3>
    <p>Huffman coding is a lossless data compression algorithm. The idea is to assign variable-length codes to input characters, lengths of the assigned codes are based on the frequencies of corresponding characters. The most frequent character gets the smallest code and the least frequent character gets the largest code.</p>
      <h4>There are mainly two major parts in Huffman Coding.<br></h4><p>
1) Build a Huffman Tree from input characters.<br>
2) Traverse the Huffman Tree and assign codes to characters.</p><br>
 <h4>Steps to build Huffman Tree</h4>
<p><strong>Forward Pass:</strong><br>
  1.Sort probabilities per symbol in descending order.<br>
  2.Combine lowest two probabilities.<br>
  3.Repeat step 2 until only two probabilities remain.<br>
  4.The last 2 probabilities must have sum=1.0<br>
 </p>
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    <table class="table table-condensed table-hover">
      <thead>
      <tr>
        <th>Symbol</th>
        <th>Probability</th>
        <th>1</th>
        <th>2</th>
        <th>3</th>
        <th>4</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td>a1</td>
        <td>0.4</td>
        <td>0.4</td>
        <td>0.4</td>
        <td>0.4</td>
        <td>0.6</td>
      </tr>
      <tr>
        <td>a2</td>
        <td>0.3</td>
        <td>0.3</td>
        <td>0.3</td>
        <td>0.3</td>
        <td>0.4</td>
      </tr>
      <tr>
        <td>a3</td>
        <td>0.1</td>
        <td>0.1</td>
        <td>0.2</td>
        <td>0.3</td>
      </tr>
      <tr>
        <td>a4</td>
        <td>0.1</td>
        <td>0.1</td>
        <td>0.1</td>
        
      </tr>
      <tr>
        <td>a5</td>
        <td>0.06</td>
        <td>0.1</td>
      </tr>
      <tr>
        <td>a6</td>
        <td>0.04</td>
      </tr>
     </tbody>
    </table>
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      <p><strong>Backward Pass:</strong><br>
  1.Assign Binary code (0,1) to last two values in your preferred order.<br>
  2.Gather bits going backward and form a code.<br>
  4.Note that code down.<br></p>
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    <table class="table table-condensed table-hover">
      <thead>
      <tr>
        <th>Symbol</th>
        <th>Probability</th>
        <th>Code</th>
        <th>1</th>
        <th>2</th>
        <th>3</th>
        <th>4</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td>a1</td>
        <td>0.4</td><td>1</td>
        <td>0.4</td>
        <td>0.4</td>
        <td>0.4</td>
        <td>0.6</td>
      </tr>
      <tr>
        <td>a2</td>
        <td>0.3</td><td>00</td>
        <td>0.3</td>
        <td>0.3</td>
        <td>0.3</td>
        <td>0.4</td>
      </tr>
      <tr>
        <td>a3</td>
        <td>0.1</td><td>011</td>
        <td>0.1</td>
        <td>0.2</td>
        <td>0.3</td>
      </tr>
      <tr>
        <td>a4</td>
        <td>0.1</td><td>0100</td>
        <td>0.1</td>
        <td>0.1</td>
        
      </tr>
      <tr>
        <td>a5</td>
        <td>0.06</td><td>01010</td>
        <td>0.1</td>
      </tr>
      <tr>
        <td>a6</td>        
        <td>0.04</td><td>01011</td>

      </tr>
     </tbody>
    </table>
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   <p id="end">The Codes generated in such a way are all unique.This is how Huffman Coding makes sure that there is no ambiguity when decoding the generated bit stream.</p>   
  
  
    
      
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