812. Largest Triangle Area

 static int wing=[]()
 {
     std::ios::sync_with_stdio(false);
     cin.tie(NULL);
     return ;
 }();

 class Solution
 {
 public:
     double largestTriangleArea(vector<vector<int>>& points)
     {
         double res=;
         for(auto &i:points)
             for(auto &j:points)
                 for(auto &k:points)
                     res=max(res,0.5*abs(i[]*j[]+j[]*k[]+k[]*i[]-j[]*i[]-k[]*j[]-i[]*k[]));
         return res;
     }
 };

暴力解法，用了下二维平面中给出三个点坐标计算三角形面积的公式