JAVA DATA STRUCTURES

"Here is an incorrect pseudo code for an algorithm which is supposed to determine whetehr a String of paranthesses is balanced:"

boolean isBalanced(String input)

{

declare a character stack

while ( input has more characters)

{

read a character from input

if ( the character is a ' ( ' )

push it on the stack

else if ( the stack is not empty )

pop a character off the stack

else

return false

}

return true

}

"Give an example of an input string that is made up of only the characters ' ( ' and ' ) ' , is unbalanced, but for which this algorithm will return true. Explain what is wrong with the algorithm. Can this algorithm ever incorrectly return false when its input string is balanced string?"