add 812

fishercoder1534 · fishercoder1534 · commit 99e052505271 · 2021-07-07T14:49:14.000-07:00
diff --git a/README.md b/README.md
@@ -488,6 +488,7 @@ _If you like this project, please leave me a star._ &#9733;
 |819|[Most Common Word](https://leetcode.com/problems/most-common-word/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_819.java) |  |Easy| HashMap
 |816|[Ambiguous Coordinates](https://leetcode.com/problems/ambiguous-coordinates/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_816.java) |  |Medium| String
 |814|[Binary Tree Pruning](https://leetcode.com/problems/binary-tree-pruning/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_814.java) |  |Medium| recursion, DFS 
+|812|[Largest Triangle Area](https://leetcode.com/problems/largest-triangle-area/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_812.java) | |Easy| Array, Math, Geometry
 |811|[Subdomain Visit Count](https://leetcode.com/problems/subdomain-visit-count/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_811.java) | |Easy| HashMap
 |809|[Expressive Words](https://leetcode.com/problems/expressive-words/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_809.java) | |Medium|
 |807|[Max Increase to Keep City Skyline](https://leetcode.com/problems/max-increase-to-keep-city-skyline/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_807.java) | |Medium|
diff --git a/src/main/java/com/fishercoder/solutions/_812.java b/src/main/java/com/fishercoder/solutions/_812.java
@@ -0,0 +1,22 @@
+package com.fishercoder.solutions;
+
+public class _812 {
+    public static class Solution1 {
+        /**
+         * reference: https://www.mathopenref.com/coordtrianglearea.html
+         */
+        public double largestTriangleArea(int[][] points) {
+            double largestArea = 0.0;
+            for (int i = 0; i < points.length - 2; i++) {
+                for (int j = i + 1; j < points.length - 1; j++) {
+                    for (int k = j + 1; k < points.length; k++) {
+                        double area = Math.abs(points[i][0] * (points[j][1] - points[k][1]) + points[j][0] * (points[k][1] - points[i][1]) + points[k][0] * (points[i][1] - points[j][1])) / 2.0;
+                        largestArea = Math.max(largestArea, area);
+
+                    }
+                }
+            }
+            return largestArea;
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_812Test.java b/src/test/java/com/fishercoder/_812Test.java
@@ -0,0 +1,28 @@
+package com.fishercoder;
+
+import com.fishercoder.common.utils.CommonUtils;
+import com.fishercoder.solutions._812;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _812Test {
+    private static _812.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _812.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(2, solution1.largestTriangleArea(CommonUtils.convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[0,0],[0,1],[1,0],[0,2],[2,0]")), 0.0000001);
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(1799.0, solution1.largestTriangleArea(CommonUtils.convertLeetCodeIrregularLengths2DArrayInputIntoJavaArray("[-35,19],[40,19],[27,-20],[35,-3],[44,20],[22,-21],[35,33],[-19,42],[11,47],[11,37]")), 0.0000001);
+    }
+
+}
