Skip to content

1395. Count Number of Teams 👍

  • Time: $O(n^2)$
  • Space: $O(1)$
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
class Solution {
 public:
  int numTeams(vector<int>& rating) {
    int ans = 0;

    for (int i = 1; i < rating.size() - 1; ++i) {
      // Calculate soldiers on the left with less/greater ratings.
      int leftLess = 0;
      int leftGreater = 0;
      for (int j = 0; j < i; ++j)
        if (rating[j] < rating[i])
          ++leftLess;
        else if (rating[j] > rating[i])
          ++leftGreater;
      // Calculate soldiers on the right with less/greater ratings.
      int rightLess = 0;
      int rightGreater = 0;
      for (int j = i + 1; j < rating.size(); ++j)
        if (rating[j] < rating[i])
          ++rightLess;
        else if (rating[j] > rating[i])
          ++rightGreater;
      ans += leftLess * rightGreater + leftGreater * rightLess;
    }

    return ans;
  }
};

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
class Solution {
  public int numTeams(int[] rating) {
    int ans = 0;

    for (int i = 1; i < rating.length - 1; ++i) {
      // Calculate soldiers on the left with less/greater ratings.
      int leftLess = 0;
      int leftGreater = 0;
      for (int j = 0; j < i; ++j)
        if (rating[j] < rating[i])
          ++leftLess;
        else if (rating[j] > rating[i])
          ++leftGreater;
      // Calculate soldiers on the right with less/greater ratings.
      int rightLess = 0;
      int rightGreater = 0;
      for (int j = i + 1; j < rating.length; ++j)
        if (rating[j] < rating[i])
          ++rightLess;
        else if (rating[j] > rating[i])
          ++rightGreater;
      ans += leftLess * rightGreater + leftGreater * rightLess;
    }

    return ans;
  }
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
class Solution:
  def numTeams(self, rating: list[int]) -> int:
    ans = 0

    for i in range(1, len(rating) - 1):
      # Calculate soldiers on the left with less//greater ratings.
      leftLess = 0
      leftGreater = 0
      for j in range(i):
        if rating[j] < rating[i]:
          leftLess += 1
        elif rating[j] > rating[i]:
          leftGreater += 1
      # Calculate soldiers on the right with less//greater ratings.
      rightLess = 0
      rightGreater = 0
      for j in range(i + 1, len(rating)):
        if rating[j] < rating[i]:
          rightLess += 1
        elif rating[j] > rating[i]:
          rightGreater += 1
      ans += leftLess * rightGreater + leftGreater * rightLess

    return ans