RedundantBraces.java

/**

Given a string A denoting an expression. It contains the following operators ’+’, ‘-‘, ‘*’, ‘/’.

Chech whether A has redundant braces or not.

Return 1 if A has redundant braces, else return 0.

Note: A will be always a valid expression.



Input Format

The only argument given is string A.

Output Format

Return 1 if string has redundant braces, else return 0.

For Example

Input 1:
    A = "((a + b))"
Output 1:
    1
    Explanation 1:
        ((a + b)) has redundant braces so answer will be 1.

Input 2:
    A = "(a + (a + b))"
Output 2:
    0
    Explanation 2:
        (a + (a + b)) doesn't have have any redundant braces so answer will be 0.


**/

public class Solution {
    public int braces(String A) {
        Stack<Character> stack = new Stack<Character>();
        char[] str = A.toCharArray();
        for(char ch : str)
        {
            if(ch == ')')
            {
                char top = stack.peek();
                stack.pop();
                boolean isRedundant = true;
                
                while(top != '(')
                {
                    if(top == '+' || top == '-' || top == '*' || top == '/')
                    {
                        isRedundant = false;
                    }
                    
                    top = stack.peek();
                    stack.pop();
                }
                
                
                if(isRedundant == true)
                {
                    return 1;
                }
                
            }
            
            else
            {
                stack.push(ch);
            }
            
        }
        return 0;
    }
}