ParenthesisMatcher

package com.practice.pyusha.arrays;

import java.util.Stack;

public class ParenthesisMatcher {
	public static void main(String[] args) {
		//String input = "This {is(an) error} scenario as there is [extra opening brace(";
		//String input = "This({is not [(an)] error} scenario) [extra opening brace]";
		//String input = "This {is(an) error} scenario (as there is [)extra opening brace()]";
		//String input = "This {is(an) error} scenario )as there is [extra opening brace()]";
		String input = "{his @ is an error scenario as there is extra opening brace}";
		int pos = 1;
		System.out.println(parenthesisMatcher(input,pos));
	}
	
	static int parenthesisMatcher(String input,int pos){                                  //Time Complexity: O(n)
		Stack<Character> st = new Stack<>();                                                //Space Complexity: O(n)
		int output = 0;
		char temp_char = 0;
		int curr_count_parenthesis = 0; //incr this pntr whenever you encounter an opening brace
		int count_keeper = 0;
		if(input.equals("") || input.equals(null) || input.length()<pos)
			return -1;
		
		for(int i = 0 ;i<input.length();i++){
			char ch1 = input.charAt(i);
			if(!Character.isLetterOrDigit(ch1) && (ch1 =='('  || ch1 == '{' || ch1 == '[')){
				curr_count_parenthesis++;
				count_keeper++;
				st.push(ch1);
				if(count_keeper == pos){
					temp_char = ch1;
				}
			}
			else if(!Character.isLetterOrDigit(ch1) && (ch1 ==')'  || ch1 == '}' || ch1 == ']')){
				if(!st.isEmpty() && isMatchingPair(st.peek(),ch1)){
					st.pop();
					curr_count_parenthesis--;
					if(count_keeper == pos && ch1 == getMatchingPair(temp_char)){
						output = i;
					}
					else if(count_keeper == pos && ch1 == getMatchingPair(temp_char))
						return -1;
				}
				else
					return -1;
			}
		}
		
		if(curr_count_parenthesis != 0 || pos>count_keeper)
			return -1;
		return output;
	}
	
	static boolean isMatchingPair(char character1, char character2)
    {
       if (character1 == '(' && character2 == ')')
         return true;
       else if (character1 == '{' && character2 == '}')
         return true;
       else if (character1 == '[' && character2 == ']')
         return true;
       else
         return false;
    }
	
	static char getMatchingPair(char character1)
    {
       if (character1 == '(')
         return ')';
       else if (character1 == '{' )
         return '}';
       else if (character1 == '[')
         return ']';
       else
    	   return 'n';
     
    }

}