CareerCup

Let us start by understanding the problem.
Here are a few examples:

( )               --  correct
   ( ( ) )           --  correct
   ( ( ) ) ( )       --  correct
   ( ( ( ) ) ( ) )   --  correct
   ( ) )             --  incorrect (closed paren with no open paren)
   ) (               --  incorrect
   ( ( ) ) ) (       --  incorrect

As you can see, the number of open and closed parens being equal does not guarantee that the parens are matching. Their order is important too.

We take care of this order using a stack.

An algorithm that checks whether the matching in a given text is correct is as follows:

0. Create an empty stack S.
  1. While( there are characters left ){
  2.   Read a character ch. 
  3.   If is ch an opening paren (of any kind), push it onto S
  4.   Else 
  5.      If  ch  is a closing paren (of any kind), look at the top of S.
  6.        If S is empty as this point, report failure. 
  7.        If the top of S is the opening paren that corresponds to c,
            then pop S and continue to 1, this paren matches OK.
  8.        Else report failure.  
  9. If at the end of input the stack S is not empty, return failure.
     Else return success.

public static boolean correctBrackets(String str) {

		int open = 0;

		for (char c : str.toCharArray()) {
			if ('{' == c)
				open++;
			else if ('}' == c && open > 0)
				open--;
			else if ('}' == c && open < 1)
				return false;
		}

		if (open == 0)
			return true;
		return false;
	}

public static void paranthesis() {

String str = "{}{{}}{}}";
int i = 0,count=0;

while(i<str.length()){

char c1 = str.charAt(i++);

if(c1=='{')
count = count +1;
else
count = count -1;

if(count<0){
System.out.println("noo! ");
break;
}
}

if(count>0)
System.out.println("noo ");
else if(count==0)
System.out.println("yes ");

}

bool paranthesis(char str[])
{
int i=0, count = 0;

for(i=0; i < strlen(str); i++)
{
if(str[i] == '}')
    count++;
else if(str[i] == '{')
{
count--;
if(count == -1)
{
printf("Paranthesis don't match")
exit(0);
}
}
}
}