find the largest substring that contains all of occurrence of a character : <p>I need to find out largest sub string that contains all of occurrence of a character in C#.</p>

<p>Example  - Input string : "my name is granar"
Nee to find out largest sub string that contains all of occurrence of a character "a", the result is "<strong>ame is grana</strong>"</p>

<p>Please help me in algorithm?</p>
