Question

WRITE IN JAVA PLEASE~

A string may use more than one type of delimiter to bracket information into "blocks". The primary ways to divide things up into block is by the braces { } , parentheses ( ), and brackets [ ] as delimiters.

• A string is considered properly delimited if each right delimiter ] } or )( is matched with a preceding left delimiter { [ ( of the same type in such a way that either the resulting blocks of information are disjoint or one of them is contained nested within the other.  
• Write a method that accepts a string in as a parameter and returns back a boolean value determining if the string is properly delimited.
• Read the string char by char, ignoring all symbols but the [,{,(,},)]. Symbols.
  • if it is an open delimiter add it to the stack
  • if it is a close delimiter check two things
    • is the stack empty?
    • is the top of the stack the correct open type.
• At the end of the string, if you haven't already returned an answer
  • Check that the stack is empty.
• Use a single stack to check whether a string containing brackets is or is not properly delimited.
• Test your method on the following strings:

• String string1 = "[{}]";
  • good
• String string2 = "[x{12345}xxx]xxx";
  • good
• String string3 = "[1{2(3)4}5]";
  • good
• String string4 = "[][](){}";
  • good
• String string5 = "[[]}";
  • bad
• String string6 = "[])";
  • bad
• String string7 = "[]123{}123()123[{}]";
  • good
• String string8 = "[[[[[]]]]]((((())))){{{{{{{{{{[]}}}}}}}}}}";
  • good
• String string9 = "[[[[[]]]]]((((())))){{{{{{{{{{[]}}}}}}}}]}";
  • bad
• String string10 = "[{({({({([[]])})})})}][{}]{}{{}}";
  • good
• String string11 = "[{(";
  • bad
• String math = "2+(3+5*(5+7-4)*[1+2+3+(6/5)])/(2*a)";
  • good

Answer 1

CODE:

import java.util.*;
import java.io.*;

public class CheckParanthesis {
public static boolean checkbalance(String str)
{
//Defining a stack.
Stack<Character> stack = new Stack<Character>();
for(int i=0;i<str.length();i++)
{
//taking each character at a time.
char ch=str.charAt(i);
//if the character is anything other than delimiters, we will ignore it.
if(ch!='(' && ch!='[' && ch!='{' && ch!=')' && ch!=']' && ch!='}')
continue;
//if the character is an open delimiter we push it in the stack.
if(ch=='(' || ch=='[' || ch=='{')
{
stack.push(ch);
continue;
}
//If its not an opening delimiter or a character, it must be a closing delimiter. And so, there must be an opening delimeter in the stack.
if(stack.isEmpty())
return false;//if the stack is empty, then there is no opening delimiter and therefore it is an invalid expression.
if(ch==')' || ch==']' || ch=='}')//if the character is a closing delimter.
{
char x=stack.pop();//pop the last entered stack value. or the value in the top of the stack
//if they dont match we return false.
if(ch=='}' && x!='{')
return false;
if(ch==')' && x!='(')
return false;
if(ch==']' && x!='[')
return false;
}
}
return stack.isEmpty();//if the stack is not empty it will return false, else true.
}
public static void main(String[] args)
{
Scanner in=new Scanner(System.in);
System.out.println("Enter a String: ");
String str=in.nextLine();
if(checkbalance(str))
{
System.out.println("good");
}
else
{
System.out.println("bad");
}
}
}

import java.util.*;
import java.io.*;

public class CheckParanthesis {
    public static boolean checkbalance(String str)
    {
        //Defining a stack.
        Stack<Character> stack = new Stack<Character>();
        for(int i=0;i<str.length();i++)
        {
            //taking each character at a time.
            char ch=str.charAt(i);
            //if the character is anything other than delimiters, we will ignore it. 
            if(ch!='(' && ch!='[' && ch!='{' && ch!=')' && ch!=']' && ch!='}')
                continue;
            //if the character is an open delimiter we push it in the stack.
            if(ch=='(' || ch=='[' || ch=='{')
            {
                stack.push(ch);
                continue;
            }
            //If its not an opening delimiter or a character, it must be a closing delimiter. And so, there must be an opening delimeter in the stack.
            if(stack.isEmpty())
                return false;//if the stack is empty, then there is no opening delimiter and therefore it is an invalid expression. 
            if(ch==')' || ch==']' || ch=='}')//if the character is a closing delimter.
            {
                char x=stack.pop();//pop the last entered stack value. or the value in the top of the stack
                //if they dont match we return false.
                if(ch=='}' && x!='{')
                    return false;
                if(ch==')' && x!='(')
                    return false;
                if(ch==']' && x!='[')
                    return false;
            }
        }
        return stack.isEmpty();//if the stack is not empty it will return false, else true.
    }
    public static void main(String[] args)
    {
        Scanner in=new Scanner(System.in);
        System.out.println("Enter a String: ");
        String str=in.nextLine();
        if(checkbalance(str))
        {
            System.out.println("good");
        }
        else
        {
            System.out.println("bad");
        }
    }
}

OUTPUT:

If you have any doubts or require any clarifications, please leave a comment and i will answer it. Thank you :)