/*遍历所有3个店组合可能,求3边,海伦公式求面积 sqrt((a+b+c)*(a+b-c)*(a+c-b)*(b+c-a))/4 */
double largestTriangleArea(int** points, int pointsSize, int* pointsColSize){ double area=0,a,b,c; for (int i=0; i<pointsSize-2; i++) for (int j=i+1; j<pointsSize-1; j++) for (int k=j+1; k<pointsSize; k++){ a = sqrt(pow(abs(points[i][0] - points[j][0]),2) + pow(abs(points[i][1] - points[j][1]),2)); b = sqrt(pow(abs(points[i][0] - points[k][0]),2) + pow(abs(points[i][1] - points[k][1]),2)); c = sqrt(pow(abs(points[j][0] - points[k][0]),2) + pow(abs(points[j][1] - points[k][1]),2)); area = (sqrt((a+b+c)*(a+b-c)*(a+c-b)*(b+c-a))/4 > area)? sqrt((a+b+c)*(a+b-c)*(a+c-b)*(b+c-a))/4: area; } return area; }