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822. Card Flipping Game 👎

  • Time: $O(n)$
  • Space: $O(n)$
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class Solution {
 public:
  int flipgame(vector<int>& fronts, vector<int>& backs) {
    constexpr int kMax = 2001;
    int ans = kMax;
    unordered_set<int> same;

    for (int i = 0; i < fronts.size(); ++i)
      if (fronts[i] == backs[i])
        same.insert(fronts[i]);

    for (const int front : fronts)
      if (!same.contains(front))
        ans = min(ans, front);

    for (const int back : backs)
      if (!same.contains(back))
        ans = min(ans, back);

    return ans == kMax ? 0 : ans;
  }
};

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class Solution {
  public int flipgame(int[] fronts, int[] backs) {
    final int kMax = 2001;
    int ans = kMax;
    Set<Integer> same = new HashSet<>();

    for (int i = 0; i < fronts.length; ++i)
      if (fronts[i] == backs[i])
        same.add(fronts[i]);

    for (final int front : fronts)
      if (!same.contains(front))
        ans = Math.min(ans, front);

    for (final int back : backs)
      if (!same.contains(back))
        ans = Math.min(ans, back);

    return ans == kMax ? 0 : ans;
  }
}

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class Solution:
  def flipgame(self, fronts: list[int], backs: list[int]) -> int:
    same = {front
            for front, back in zip(fronts, backs)
            if front == back}
    return min([num for num in fronts + backs
                if num not in same] or [0])