ParenthesesBalance.java

/** https://uva.onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=614 #stack */
import java.util.Deque;
import java.util.LinkedList;
import java.util.Scanner;

class ParenthesesBalance {
  static Character validPairChar(Character c) {
    if (c == ']') {
      return '[';
    } else if (c == ')') {
      return '(';
    } else {
      return c;
    }
  }

  static String check(String str) {
    Deque<Character> stack = new LinkedList<>();
    for (Character c : str.toCharArray()) {
      if (c == '(' || c == '[') {
        stack.addFirst(c);
      } else {
        if (stack.isEmpty() || stack.peekFirst() != validPairChar(c)) {
          return "No";
        } else {
          stack.pollFirst();
        }
      }
    }
    if (!stack.isEmpty()) {
      return "No";
    }
    return "Yes";
  }

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    // sc.nextLine();

    String[] arr = new String[n];
    for (int i = 0; i < n; i++) {
      String str = sc.next(); // sc.nextLine();
      arr[i] = str;
    }
    for (String str : arr) {
      System.out.println(check(str));
    }
  }
}