Create LargestTriangleArea.java

src/codingquestions/leetcode/LargestTriangleArea.java

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+/*
+812. Largest Triangle Area
+Solved
+Easy
+Topics
+premium lock icon
+Companies
+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.
+*/
+class Solution {
+    private int doubleArea(int[] a, int[] b, int[] c){
+        //return AB x AC
+        int res = (b[0] - a[0]) * (c[1] - a[1]) - (b[1] - a[1]) * (c[0] - a[0]);
+        return Math.abs(res);
+    }
+    public double largestTriangleArea(int[][] points) {
+        int res = 0;
+        for(int i = 0; i < points.length; i++)
+            for(int j = i + 1; j < points.length; j++)
+                for(int k = j + 1; k < points.length; k++)
+                    res = Math.max(res, doubleArea(points[i], points[j], points[k]));
+
+        double ans = (double)(res) / 2.0;
+        return ans;
+    }
+}