题目描述：

LeetCode 812. Largest Triangle Area

You have a list of points in the plane. Return the area of the largest triangle that can be formed by any 3 of the points.

Example:
Input: points = [[0,0],[0,1],[1,0],[0,2],[2,0]]
Output: 2
Explanation: 
The five points are show in the figure below. The red triangle is the largest.

Notes:

• 3 <= points.length <= 50.
• No points will be duplicated.
•  -50 <= points[i][j] <= 50.
• Answers within 10^-6 of the true value will be accepted as correct.

题目大意：

给定平面上一组点坐标，求任意三点构成三角形的最大面积。

解题思路：

Shoelace formula （根据顶点坐标求三角形面积）

枚举点坐标，套用公式即可

Python代码：

class Solution(object):
    def largestTriangleArea(self, points):
        """
        :type points: List[List[int]]
        :rtype: float
        """
        triangleArea = lambda x1, y1, x2, y2, x3, y3: \
            abs(0.5 * (x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2)))
        size = len(points)
        ans = 0
        for i in range(size):
            for j in range(i + 1, size):
                for k in range(j + 1, size):
                    x1, y1 = points[i]
                    x2, y2 = points[j]
                    x3, y3 = points[k]
                    ans = max(ans, triangleArea(x1, y1, x2, y2, x3, y3))
        return ans

 

本文链接：http://bookshadow.com/weblog/2018/04/09/leetcode-largest-triangle-area/
请尊重作者的劳动成果，转载请注明出处！书影博客保留对文章的所有权利。

如果您喜欢这篇博文，欢迎您捐赠书影博客： ，查看支付宝二维码