First non-repeating character in a string?

Logic

• Count character frequency.
• Traverse string again to find the first with count = 1.

string input = "swiss";
Dictionary<char, int> map = new Dictionary<char, int>();
foreach (char c in input)
map[c] = map.ContainsKey(c) ? map[c] + 1 : 1;
foreach (char c in input)
{
if (map[c] == 1)
{

Console.WriteLine(c);

break;

}
}