CardFilipGame.java

/* (C) 2024 YourCompanyName */
package array;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Created by gouthamvidyapradhan on 04/05/2018.
 *
 * <p>On a table are N cards, with a positive integer printed on the front and back of each card
 * (possibly different).
 *
 * <p>We flip any number of cards, and after we choose one card.
 *
 * <p>If the number X on the back of the chosen card is not on the front of any card, then this
 * number X is good.
 *
 * <p>What is the smallest number that is good? If no number is good, output 0.
 *
 * <p>Here, fronts[i] and backs[i] represent the number on the front and back of card i.
 *
 * <p>A flip swaps the front and back numbers, so the value on the front is now on the back and vice
 * versa.
 *
 * <p>Example:
 *
 * <p>Input: fronts = [1,2,4,4,7], backs = [1,3,4,1,3] Output: 2 Explanation: If we flip the second
 * card, the fronts are [1,3,4,4,7] and the backs are [1,2,4,1,3]. We choose the second card, which
 * has number 2 on the back, and it isn't on the front of any card, so 2 is good.
 *
 * <p>Note:
 *
 * <p>1 <= fronts.length == backs.length <= 1000. 1 <= fronts[i] <= 2000. 1 <= backs[i] <= 2000.
 */
public class CardFilipGame {

  public static void main(String[] args) {}

  public int flipgame(int[] fronts, int[] backs) {
    List<Integer> numbers = new ArrayList<>();
    for (int i = 0; i < fronts.length; i++) {
      numbers.add(fronts[i]);
      numbers.add(backs[i]);
    }
    Collections.sort(numbers);
    for (int n : numbers) {
      boolean success = true;
      for (int i = 0; i < fronts.length; i++) {
        if (n == fronts[i] && n == backs[i]) {
          success = false;
          break;
        }
      }
      if (success) {
        return n;
      }
    }
    return 0;
  }
}