solution.cpp

/**
 * 57 / 57 test cases passed.
 * Runtime: 8 ms
 * Memory Usage: 7.4 MB 
 */
class Solution {
public:
    double traingleArea(int x1, int y1, int x2, int y2, int x3, int y3) {
        return abs(x1 * y2 + x2 * y3 + x3 * y1 - x1 * y3 - x2 * y1 - x3 * y2) * 0.5;
    }
    double largestTriangleArea(vector<vector<int>>& points) {
        int n = points.size();
        double ans = 0.0;
        for (int i = 0; i < n; ++ i) {
            for (int j = i + 1; j < n; ++ j) {
                for (int k = j + 1; k < n; ++ k) {
                    int x1 = points[i][0], y1 = points[i][1];
                    int x2 = points[j][0], y2 = points[j][1];
                    int x3 = points[k][0], y3 = points[k][1];
                    ans = max(ans, traingleArea(x1, y1, x2, y2, x3, y3));
                }
            }
        }
        return ans;
    }
};