[leetcode] 812. Largest Triangle Area

[leetcode] 812. Largest Triangle Area

Description

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: 2Explanation: 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.

分析

题目的意思是：给你一堆点，从其中选择三个点构成三角形，求能够成的最大的面积。

根据坐标求三角形的面积，公式需要推导，通过S=0.5AB*sin© 推导而来。本质上还是把所有的可能列举出来，然后暴力破解。

代码

class Solution {public: double largestTriangleArea(vector>& points) { double res=0; for(auto i:points){ for(auto j:points){ for(auto k:points){ res=max(res,solve(i,j,k)); } } } return res; } double solve(vectori,vector j,vector k){ return 0.5*abs(i[0]*j[1]+j[0]*k[1]+k[0]*i[1]-j[0]*i[1]-k[0]*j[1]-i[0]*k[1]); }};

参考文献

​​812. Largest Triangle Area​​

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