coding bat recursion :Given a string, return true if it is a nesting of zero or more pairs of parenthesis, like "(())" or "((()))". Suggestion: check the first and last chars, and then recur on what's inside them.

nestParen("(())") → true
nestParen("((()))") → true
nestParen("(((x))") → false


solution:

public boolean nestParen(String str)
{
   return nest(str,0,str.length()-1);
}
public boolean nest(String str,int start,int end) {
 if(start>end)
 {
   return true;
 }
 else if(str.charAt(start)=='(' && str.charAt(end)==')')
 {
   return nest(str,start+1,end-1);
 }
 else
 {
   return false;
 }
}