Skip to content

2869. Minimum Operations to Collect Elements 👍

  • Time: $O(n)$
  • Space: $O(k)$
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
class Solution {
 public:
  int minOperations(vector<int>& nums, int k) {
    unordered_set<int> seen;

    for (int i = nums.size() - 1; i >= 0; --i) {
      if (nums[i] > k)
        continue;
      seen.insert(nums[i]);
      if (seen.size() == k)
        return nums.size() - i;
    }

    throw;
  }
};

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
class Solution {
  public int minOperations(List<Integer> nums, int k) {
    Set<Integer> seen = new HashSet<>();

    for (int i = nums.size() - 1; i >= 0; --i) {
      if (nums.get(i) > k)
        continue;
      seen.add(nums.get(i));
      if (seen.size() == k)
        return nums.size() - i;
    }

    throw new IllegalArgumentException();
  }
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
class Solution:
  def minOperations(self, nums: list[int], k: int) -> int:
    seen = set()

    for i, num in enumerate(reversed(nums)):
      if num > k:
        continue
      seen.add(num)
      if len(seen) == k:
        return i + 1