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LeetCode Solutions

251. Flatten 2D Vector

Time: $O(n)$

Space: $O(n)$

			


class Vector2D {
 public:
  Vector2D(vector<vector<int>>& vec) {
    for (const vector<int>& A : vec)
      for (const int a : A)
        this->vec.push_back(a);
  }

  int next() {
    return vec[i++];
  }

  bool hasNext() {
    return i < vec.size();
  }

 private:
  vector<int> vec;
  int i = 0;
};




			


class Vector2D {
  public Vector2D(int[][] vec) {
    for (int[] A : vec)
      for (final int a : A)
        this.vec.add(a);
  }

  public int next() {
    return vec.get(i++);
  }

  public boolean hasNext() {
    return i < vec.size();
  }

  private List<Integer> vec = new ArrayList<>();
  private int i = 0;
}




			


class Vector2D:
  def __init__(self, vec: List[List[int]]):
    self.vec = []
    self.i = 0

    for A in vec:
      self.vec += A

  def next(self) -> int:
    ans = self.vec[self.i]
    self.i += 1
    return ans

  def hasNext(self) -> bool:
    return self.i < len(self.vec)