Today I have done leetcode's September LeetCoding Challenge with cpp.

September LeetCoding Challenge 27

Description

Largest Triangle Area

Given an array of points on the X-Y plane points where points[i] = [xi, yi], return the area of the largest triangle that can be formed by any three different points. Answers within 10-5 of the actual answer will be accepted.

Example 1:

Input: points = [[0,0],[0,1],[1,0],[0,2],[2,0]]
Output: 2.00000
Explanation: The five points are shown in the above figure. The red triangle is the largest.

Example 2:

Input: points = [[1,0],[0,0],[0,1]]
Output: 0.50000

Constraints:

• 3 <= points.length <= 50
• -50 <= xi, yi <= 50
• All the given points are unique.

Solution

class Solution {
public:
  double largestTriangleArea(vector<vector<int>>& points) {
    double mmax = 0;
    int n = points.size();
    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) {
          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];
          double area = 0.5 * abs(x1*(y2 - y3) + x2*(y3 - y1) + x3*(y1 - y2));
          mmax = max(mmax, area);
        }
      }
    }
    return mmax;
  }
};

// Accepted
// 57/57 cases passed (0 ms)
// Your runtime beats 100 % of cpp submissions
// Your memory usage beats 87.28 % of cpp submissions (10.4 MB)