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  1. Prepare
  2. Java
  3. Data Structures
  4. Java Stack
  5. Discussions

Java Stack

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651 Discussions

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  • bdeesorn
     + 0 comments
    private static boolean isMatch(String line) {
        if (line.length()%2 != 0) {
            return false;
        }
        
        Stack<Integer> intStack = new Stack<>();
        for (char c : line.toCharArray()) {
            switch (c) {
                case '[':
                    intStack.push(1);
                    break;
                case '{':
                    intStack.push(2);
                    break;
                case '(':
                    intStack.push(3);
                    break;
                case ')':
                    intStack.push(4);
                    break;
                case '}':
                    intStack.push(5);
                    break;
                case ']':
                    intStack.push(6);
                    break;
                default:
                    //
            }
        }
        
        Stack<Integer> leftoverStack = new Stack<>();
        
        while (intStack.size() > 0) {
            if (leftoverStack.isEmpty()) {
                leftoverStack.push(intStack.pop());
            } else {
                if (intStack.peek() + leftoverStack.peek() == 7 &&
                        intStack.peek() < leftoverStack.peek()) {
                    intStack.pop();
                    leftoverStack.pop();
                } else {
                    leftoverStack.push(intStack.pop());
                }
            }
        }
        
        return leftoverStack.isEmpty();
    }

  • Damian_GDO_92
     + 0 comments
    import java.util.*;
class Solution{
	
	public static void main(String []argh)
	{
		Scanner sc = new Scanner(System.in);
        
        Map<Character, Character> parentheses = new HashMap<>();
        parentheses.put(')', '(');
        parentheses.put(']', '[');
        parentheses.put('}', '{');
        
		while (sc.hasNext()) {
			String input = sc.next();
            boolean isBalanced = true;
            
            Stack<Character> stack = new Stack<>();
            
            for (int i = 0; i < input.length(); i++) {
                char c = input.charAt(i);
            
                if (c == '(' || c == '[' || c == '{') {
                    stack.add(c);
                } else {
                    if (stack.isEmpty() || stack.pop() != parentheses.get(c)) {
                        isBalanced = false;
                        break;
                    }
                }
            }
            
            if (!stack.isEmpty()) {
                isBalanced = false;
            }
            System.out.println(isBalanced);
		}
		
	}
}

  • spriyamalar
     + 0 comments
    public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    while (sc.hasNext()) {
        String input=sc.next();
        boolean valid = input.length() % 2 == 0;
        Stack<Character> charStack = new Stack<>();
        for(int i=0; valid && i<input.length();i++) {
            Character c = input.charAt(i);
            if(List.of('[', '{', '(').contains(c)) {
                charStack.push(c);
            } else {
                if(charStack.isEmpty()) {
                    valid = false;
                    break;
                }
                Character p = charStack.pop();
                if((c == '}' && p != '{') || 
                   (c == ']' && p != '[') ||
                   (c == ')' && p != '(')) {
                    valid = false;
                    break;
                }
            }
        }
        if(!charStack.isEmpty()) valid = false;
        System.out.println(valid ? true : false);
    }

    }

  • yashdeora98294
     + 0 comments

    Here is Java Stack solution - https://programmingoneonone.com/hackerrank-java-stack-problem-solution.html

  • raseen2004
     + 0 comments
    import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner sn = new Scanner(System.in);
				
        while(sn.hasNextLine()){
            String str = sn.nextLine();
            boolean isBalanced = isBalanced(str);
            System.out.println(isBalanced);
        }
        
    }
    
    public static boolean isBalanced(String s){
        Stack<Character> stack  = new Stack<>();
        
        for(char ch: s.toCharArray()){
            if(ch=='(' || ch=='{' || ch=='['){
                stack.push(ch);
            }else if(ch==')' || ch=='}' || ch==']'){
                if(stack.isEmpty()) return false;
                char top = stack.pop();
                
                if( ( ch==')' && top != '(' ) || ( ch=='}' && top != '{' ) || ( ch==']' && top != '[' ) ){
                    return false;
                }
                
            }
        }
        
        return stack.isEmpty();
    } 
}