Algorithms/1395_Count_Number_of_Teams.cpp at master · ketkimnaik/Algorithms · GitHub

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class Solution {
public:
    int numTeams(vector<int>& rating) {
        int n=rating.size();
        int k= count(rating);                           //            for > > case
        reverse(rating.begin(),rating.end());
        k+=(count(rating));                                   //             for < < case
        return k;

    }

    int count(vector<int>& rating){
        int n=rating.size();
        vector<int> greater(n);             //greater [i] store count of elements greater than rating[i] on right side
        vector<int> smaller(n);            // smaller [i] stores count of elements smaller than rating[i] on left side
        for(int i=0;i<n;i++){
            int target=rating[i];
            int c=0;
            for(int j=i+1;j<n;j++){
                if(rating[j]>target)
                    c++;
            }
            greater[i]=c;
        }

        for(int i=0;i<n;i++){
            int target=rating[i];
            int c=0;
            for(int j=i-1;j>=0;j--){
                if(rating[j]<target)
                    c++;
            }
            smaller[i]=c;
        }
        int sum=0;
        for(int i=0;i<n;i++)
            sum+=(greater[i]*smaller[i]);                    //Total triplets with A[i] as middle element in (  <A[i] < ) this case
        return sum;

    }
};

Brute Force

class Solution {
public:
    int numTeams(vector<int>& s) {


        int n=s.size();
        if(n<3)
            return 0;
         int sum=0;
        for(int i=0;i<n-2;i++)
        {
            for(int j=i+1;j<n-1;++j)
            {
                for(int k=j+1;k<n;++k)
                {
                    if(s[k]>s[j] && s[j]>s[i])
                        sum+=1;
                }
            }

        }

        for(int i=n-1;i>=2;--i)
        {
            for(int j=i-1;j>=1;--j)
            {
                for(int k=j-1;k>=0;--k)
                {
                    if(s[k]>s[j] && s[j]>s[i])
                        sum+=1;
                }
            }

        }

        return sum;

    }
};