LeetCode – Arrays – Count Number of Teams

There are n soldiers standing in a line. Each soldier is assigned a unique rating value.

You have to form a team of 3 soldiers amongst them under the following rules:

• Choose 3 soldiers with index (i, j, k) with rating (rating[i], rating[j], rating[k]).
• A team is valid if:  (rating[i] < rating[j] < rating[k]) or (rating[i] > rating[j] > rating[k]) where (0 <= i < j < k < n).

Return the number of teams you can form given the conditions. (soldiers can be part of multiple teams).

Example 1:

Input: rating = [2,5,3,4,1]
Output: 3
Explanation: We can form three teams given the conditions. (2,3,4), (5,4,1), (5,3,1). 

Example 2:

Input: rating = [2,1,3]
Output: 0
Explanation: We can't form any team given the conditions.

Example 3:

Input: rating = [1,2,3,4]
Output: 4

class Solution {
    public int numTeams(int[] rating) {
        List<Integer> subTeams = new ArrayList<Integer>();
        int counter = 0;
            
        for(int i=0;i<rating.length;i++){
            subTeams.add(rating[i]);
            for(int j=i+1;j+1<rating.length;j++){
                if(rating[i]<rating[j] || rating[i]>rating[j]){
                    subTeams.add(rating[j]);
                    for(int k=j+1;k<rating.length;k++){
                        if((rating[i]<rating[j] && rating[j]<rating[k]) ||
                           (rating[i]>rating[j] && rating[j]>rating[k])){
                            subTeams.add(rating[k]);
                            if(subTeams.size() == 3){
                                counter++;
                                subTeams.remove(2);
                            }
                        }     
                    }
                    subTeams.remove(1);
                }
            }
            subTeams.remove(0);
        }
        return counter;
    }
}