Please answer the questiong correctly, show approprite code and output of compil
ID: 3867283 • Letter: P
Question
Please answer the questiong correctly, show approprite code and output of compiled code.
Balanced Parentheses [10 marks]
A stack is a data structure where data is accessed using the LIFO (last in first out) principle. In this problem, you will use a stack to check whether a string has balanced parentheses (, ) and brackets {, }, [, ], or not.
A string that has balanced parentheses and brackets will be said to be balanced. Any character that is not one of (, ), [, ], {, or } is not important when deciding if a string is balanced and can be ignored.
We will define balanced as follows. A string str is balanced
if str does not contain a parenthesis or bracket symbol, or
str consists of a balanced string surrounded by opening and closing parentheses or matching brackets. That is, str is (b), {b} or [b], where b is any balanced string, or
if str is the concatenation of any two balanced strings. That is, str is bc, where b and c are any balanced strings.
You will complete the provided Balanced class that has two static methods isBalanced(String) and numberOfBalancedStrings(String[]).
Your isBalanced method must use the java.util.Stack class (in a way that solves the problem) to receive any grades for this problem.
http://docs.oracle.com/javase/8/docs/api/java/util/Stack.html
Examples
The following strings have balanced parentheses
(), ()()
cat, c(at), (hello)(kitty)
if( ((x-y) < 4) || (x > 12))
()(((s)))()()()()(x()((y))(x))()(ccccc(w))ssss()
The following strings do not have balances parentheses
), )(a), )a(
The following strings have balanced parentheses and brackets
a, [], {}, [()], []{}({[{}]}),
for(int i=0; i<12; i+=1){x[i]+=f(1);}
The following strings do not have balanced parentheses and brackets
(], {), [}, [}, (], ({)}h, [(]())
for(int i=0; i<12; i+=1){
Note: You will receive partial marks if you code only works for parentheses (and not brackets).
BALANCED.JAVA
import java.util.Stack; public class Balanced{ /** Checks if a string is balanced or not. @param s is a non-null string @return true of the input <code>s</code> is balanced and false otherwise. **/ public static boolean isBalanced(String s){ return false; } /** Counts the number of balanced strings in the input array. @param in is a non-null array of strings @return the number of strings in the input< code>in</code> that are balanced. **/ public static int numberOfBalancedStrings(String[] in){ return -1; } }Explanation / Answer
import java.util.Stack;
/**
*
* @author Sam
*/
public class Balanced {
/**
* Checks if a string is balanced or not.
*
* @param s is a non-null string
* @return true of the input <code>s</code> is balanced and false otherwise.
*
*/
public static boolean isBalanced(String s) {
Stack<Character> stack = new Stack<>();
for (int i = 0; i < s.length(); i++)
if (s.charAt(i) == '(' || s.charAt(i) == '{' || s.charAt(i) == '[')
stack.push(s.charAt(i));
else if (s.charAt(i) == ')' ) {
if (stack.pop() != '(')
return false;
}
else if (s.charAt(i) == '}') {
if (stack.pop() != '{')
return false;
}
else if (s.charAt(i) == ']') {
if (stack.pop() != '[')
return false;
}
return stack.isEmpty();
}
/**
* Counts the number of balanced strings in the input array.
*
* @param in is a non-null array of strings
* @return the number of strings in the input< code>in</code> that are
* balanced.
*
*/
public static int numberOfBalancedStrings(String[] in) {
int count = 0;
for (String s:in)
if (isBalanced(s))
count++;
return count;
}
}
This will do your job well :) Let me know if you need any assistance!