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class Solution {
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  public String reverseParentheses(String s) {
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    Stack<String> stack = new Stack<>();
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    int j = 0;
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    while (j < s.length()) {
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      /*
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          We need to keep on adding whatever comes
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          as long as it is not a ')'.
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      */
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      if (s.charAt(j) != ')') stack.push(s.charAt(j) + "");
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      /*
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          Now that we have encountered an ')', its time
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          to start popping from top of stack unless we find an opening
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          parenthesis
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          then we just need to reverse the string formed by popping
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          and put it back on stack.
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          Try dry running and it will all make sense
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      */
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      else {
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        StringBuilder sb = new StringBuilder();
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        while (!stack.isEmpty() && !stack.peek().equals("(")) {
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          sb.append(stack.pop());
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        }
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        stack.pop();
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        stack.push(sb.reverse().toString());
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      }
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      j++;
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    }
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    /*
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        We have our result string in the stack now,
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        we just need to pop it and return the reverse of it.
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    */
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    StringBuilder res = new StringBuilder();
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    while (!stack.isEmpty()) res.append(stack.pop());
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    return res.reverse().toString();
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  }
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}