Add solution #497

Author: JoshCrozier

README.md

@@ -398,6 +398,7 @@
 494|[Target Sum](./0494-target-sum.js)|Medium|
 495|[Teemo Attacking](./0495-teemo-attacking.js)|Easy|
 496|[Next Greater Element I](./0496-next-greater-element-i.js)|Easy|
+497|[Random Point in Non-overlapping Rectangles](./0497-random-point-in-non-overlapping-rectangles.js)|Medium|
 500|[Keyboard Row](./0500-keyboard-row.js)|Easy|
 501|[Find Mode in Binary Search Tree](./0501-find-mode-in-binary-search-tree.js)|Easy|
 502|[IPO](./0502-ipo.js)|Hard|

solutions/0497-random-point-in-non-overlapping-rectangles.js

@@ -0,0 +1,47 @@
+/**
+ * 497. Random Point in Non-overlapping Rectangles
+ * https://leetcode.com/problems/random-point-in-non-overlapping-rectangles/
+ * Difficulty: Medium
+ *
+ * You are given an array of non-overlapping axis-aligned rectangles rects where
+ * rects[i] = [ai, bi, xi, yi] indicates that (ai, bi) is the bottom-left corner point of the
+ * ith rectangle and (xi, yi) is the top-right corner point of the ith rectangle. Design an
+ * algorithm to pick a random integer point inside the space covered by one of the given
+ * rectangles. A point on the perimeter of a rectangle is included in the space covered by
+ * the rectangle.
+ *
+ * Any integer point inside the space covered by one of the given rectangles should be equally
+ * likely to be returned.
+ *
+ * Note that an integer point is a point that has integer coordinates.
+ *
+ * Implement the Solution class:
+ * - Solution(int[][] rects) Initializes the object with the given rectangles rects.
+ * - int[] pick() Returns a random integer point [u, v] inside the space covered by one of the
+ *   given rectangles.
+ */
+
+/**
+ * @param {number[][]} rects
+ */
+var Solution = function(rects) {
+  this.rects = rects;
+  this.areas = rects.map(([x1, y1, x2, y2]) => (x2 - x1 + 1) * (y2 - y1 + 1));
+  this.totalPoints = this.areas.reduce((sum, area) => sum + area, 0);
+};
+
+/**
+ * @return {number[]}
+ */
+Solution.prototype.pick = function() {
+  let random = Math.floor(Math.random() * this.totalPoints);
+  let i = 0;
+  while (random >= this.areas[i]) {
+    random -= this.areas[i];
+    i++;
+  }
+  const [x1, y1, x2, y2] = this.rects[i];
+  const x = x1 + Math.floor(Math.random() * (x2 - x1 + 1));
+  const y = y1 + Math.floor(Math.random() * (y2 - y1 + 1));
+  return [x, y];
+};