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POCharacter Repetition
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  1. POCharacter Repetition
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    copied!<p>I am writing a simple program to calculate the repetition of characters in a string sequence. The program I have for now is as below, but I am looking to see if it can be optimized any further. I believe the program right now is O(n) worst case time and I would like to see if there is something that can give me O(log n) running time.</p> <pre><code>using System; using System.Collections.Generic; namespace Algos { class CharacterRepitition { private char[] checkStringArray; private bool[] discovered; public CharacterRepitition(string toCheck) { checkStringArray= toCheck.ToCharArray(); discovered= new bool[checkStringArray.Length]; for (int i = 0; i &lt; checkStringArray.Length; i++) { discovered[i] = false; } } public void CheckRepetitions() { int charIndex=0; Dictionary&lt;char, int&gt; repetitions = new Dictionary&lt;char, int&gt;(); while (charIndex &lt; checkStringArray.Length) { int count = 0; if(discovered[charIndex].Equals(false)) { count = RunThroughTheString(charIndex, checkStringArray); if (count &gt; 0) { repetitions.Add(checkStringArray[charIndex], count+1); } } charIndex++; } if (repetitions.Count == 0) { Console.WriteLine("\nNo characters repeated."); } else { foreach (KeyValuePair&lt;char, int&gt; result in repetitions) { Console.WriteLine("\n'"+ result.Key + "' is present: " + result.Value + " times."); } } } private int RunThroughTheString(int currentCharIndex, char[] checkStringArray) { int counter = 0; for (int i = 0; i &lt; checkStringArray.Length; i++) { if (checkStringArray[currentCharIndex].Equals(checkStringArray[i]) &amp;&amp; i !=currentCharIndex) { counter++; discovered[i] = true; } } return counter; } } } </code></pre> <p>I know i can achieve this with LINQ as well. But that is not something I am looking for. Appreciate your help.</p>
 

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