Count Number of Teams

给一个数组, 找到有多少组的i,j,k使得ary[i] < ary[j] < ary[k].

这题就o(n^2)的查找就能过.

class Solution {
public:
    int numTeams(vector<int>& r) {
        int res = 0;
        int n = r.size();
        for(int i = 0; i < n; i++){
            int countLeftInc = 0;
            int countRightInc = 0;
            int countLeftDec = 0;
            int countRightDec = 0;
            for(int j = 0; j < i; j++){
                if(r[j] < r[i]){
                    countLeftInc++;
                }
                else{
                    countLeftDec++;
                }
            }
            for(int j = i + 1; j < n; j++){
                if(r[j] > r[i]){
                    countRightInc++;
                }
                else{
                    countRightDec++;
                }
            }
            res += (countLeftInc * countRightInc);
            res += (countLeftDec * countRightDec);
        }
        return res;
    }
};