codewars #51 Simple string indices (6kyu)

#51 Simple string indices

n this Kata, you will be given a string with brackets and an index of an opening bracket and your task will be to return the index of the matching closing bracket. Both the input and returned index are 0-based except in Fortran where it is 1-based. An opening brace will always have a closing brace. Return -1 if there is no answer (Haskell return Nothing, Fortran: return 0)

For example

solve("((1)23(45))(aB)", 0) = 10 // the opening brace at index 0 matches the closing brace at index 10

solve("((1)23(45))(aB)", 1) = 3 

solve("((1)23(45))(aB)", 2) = -1 // there is no opening bracket at index 2, so return -1

solve("((1)23(45))(aB)", 6) = 9

solve("((1)23(45))(aB)", 11) = 14

solve("((>)|?(*'))(yZ)", 11) = 14

import java.util.Stack;

public class Indice {

  public static int solve(String str, int index){
   // write your code
   Stack<Integer> stack = new Stack<Integer>();
   for(int i =0 ; i < str.length(); i++){
     if(str.charAt(i) == '('){
       stack.add(i);
     }else if(str.charAt(i) == ')'){
       if(stack.pop() == index)
         return i;
     }
   }
    return -1;    
  }
}