public static string GetParenthesis(int n)
{
var result = new List <string>();
if (n < 1)
{
return(null);
}
Queue <ParenthesisItem> queue = new Queue <ParenthesisItem>();
var currentItem = new ParenthesisItem();
currentItem.AddOpen(currentItem);
queue.Enqueue(currentItem);
while (queue.Count > 0)
{
var current = queue.Dequeue();
if (current.Count == 2 * n)
{
result.Add(current.Output);
continue;
}
if (current.OpenCount < n)
{
var tempItem = new ParenthesisItem();
tempItem.AddOpen(current);
queue.Enqueue(tempItem);
}
if (current.CloseCount < current.OpenCount)
{
var tempItem = new ParenthesisItem();
tempItem.AddClose(current);
queue.Enqueue(tempItem);
}
}
var sb = new StringBuilder();
result.ForEach(res => sb.Append(res + ", "));
return(sb.Length > 2 ? sb.ToString().Substring(0, sb.Length - 2) : sb.ToString());
}
public void AddClose(ParenthesisItem item)
{
sb = new StringBuilder(item.Output);
OpenCount = item.OpenCount;
sb.Append(')');
}
public void AddOpen(ParenthesisItem item)
{
sb = new StringBuilder(item.Output);
sb.Append('(');
OpenCount = item.OpenCount + 1;
}