leetcode 812. Largest Triangle Area ( Python )

描述

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.

解析

根据题意，暴力破解，遍历各个点的组合，根据公式计算面积取最大值即可，时间复杂度为 O(N^3)，空间复杂度为 O(1)。

解答

class Solution(object):
def largestTriangleArea(self, points):
    """
    :type points: List[List[int]]
    :rtype: float
    """
    def f(p1, p2, p3):
        (x1, y1), (x2, y2), (x3, y3) = p1, p2, p3
        return 0.5 * abs(x1 * (y2 - y3) + x2 * (y3 - y1) + x3 * (y1 - y2))
    return max(f(a, b, c) for a, b, c in itertools.combinations(points, 3))

                
                 	      
		

运行结果

Runtime: 96 ms, faster than 87.76% of Python online submissions for Largest Triangle Area.
Memory Usage: 11.8 MB, less than 65.22% of Python online submissions for Largest Triangle Area.

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