solves rectangle area in java

Author: anishLearnsToCode

Diff for: README.md

@@ -180,7 +180,7 @@
 | 220  | [Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii)                                                                            |                                                              [![Java](assets/java.png)](src/ContainsDuplicateIII.java)                                                               |                                                                                                                                   |
 | 221  | [Maximal Square](https://leetcode.com/problems/maximal-square)                                                                                            |                                                                  [![Java](assets/java.png)](src/MaximalSquare.java)                                                                  |                                                                                                                                   |
 | 222  | [Count Complete Tree Nodes](https://leetcode.com/problems/count-complete-tree-nodes)                                                                      |                                                             [![Java](assets/java.png)](src/CountCompleteTreeNodes.java)                                                              |                                                                                                                                   |
-| 223  | [Rectangle Area](https://leetcode.com/problems/rectangle-area)                                                                                            |                                                                                                                                                                                      |                                                                                                                                   |
+| 223  | [Rectangle Area](https://leetcode.com/problems/rectangle-area)                                                                                            |                                                                  [![Java](assets/java.png)](src/RectangleArea.java)                                                                  |                                                                                                                                   |
 | 225  | [Implement Stack using Queues](https://leetcode.com/problems/implement-stack-using-queues)                                                                |                                 [![Java](assets/java.png)](src/MyStack.java) [![Python](assets/python.png)](python/implement_stack_using_queues.py)                                  |                                                                                                                                   |
 | 226  | [Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree)                                                                                    |                                  [![Java](assets/java.png)](src/InvertBinaryTree.java) [![Python](assets/python.png)](python/invert_binary_tree.py)                                  |                                                                                                                                   |
 | 228  | [Basic Calculator II](https://leetcode.com/problems/basic-calculator-ii)                                                                                  |                                                                                                                                                                                      |                                                                                                                                   |

Diff for: src/RectangleArea.java

@@ -0,0 +1,49 @@
+// https://leetcode.com/problems/rectangle-area
+// T: O(1)
+// S: O(1)
+
+public class RectangleArea {
+    private record Point(int x, int y) {}
+
+    private static class Rectangle {
+        public final int xl;
+        public final int xr;
+        public final int yb;
+        public final int yt;
+        public final int area;
+
+        Rectangle(Point lowerLeft, Point upperRight) {
+            xl = lowerLeft.x;
+            xr = upperRight.x;
+            yb = lowerLeft.y;
+            yt = upperRight.y;
+            area = (upperRight.x - lowerLeft.x) * (upperRight.y - lowerLeft.y);
+        }
+
+        public static Rectangle from(int x1, int y1, int x2, int y2) {
+            final Point a1 = new Point(x1, y1);
+            final Point a2 = new Point(x2, y2);
+            return new Rectangle(a1, a2);
+        }
+
+        public Rectangle intersection(Rectangle other) {
+            final int intersectionXl = Math.max(xl, other.xl);
+            final int intersectionXr = Math.max(intersectionXl, Math.min(xr, other.xr));
+            final int intersectionYb = Math.max(yb, other.yb);
+            final int intersectionYt = Math.max(intersectionYb, Math.min(yt, other.yt));
+
+            if (intersectionXl > intersectionXr || intersectionYb > intersectionYt) {
+                return null;
+            }
+
+            return Rectangle.from(intersectionXl, intersectionYb, intersectionXr, intersectionYt);
+        }
+    }
+
+    public static int computeArea(int ax1, int ay1, int ax2, int ay2, int bx1, int by1, int bx2, int by2) {
+        final Rectangle rectangle1 = Rectangle.from(ax1, ay1, ax2, ay2);
+        final Rectangle rectangle2 = Rectangle.from(bx1, by1, bx2, by2);
+        final Rectangle intersection = rectangle1.intersection(rectangle2);
+        return rectangle1.area + rectangle2.area - (intersection == null ? 0 : intersection.area);
+    }
+}