Add solution #1453

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,309 LeetCode solutions in JavaScript
+# 1,310 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1110,6 +1110,7 @@
 1450|[Number of Students Doing Homework at a Given Time](./solutions/1450-number-of-students-doing-homework-at-a-given-time.js)|Easy|
 1451|[Rearrange Words in a Sentence](./solutions/1451-rearrange-words-in-a-sentence.js)|Medium|
 1452|[People Whose List of Favorite Companies Is Not a Subset of Another List](./solutions/1452-people-whose-list-of-favorite-companies-is-not-a-subset-of-another-list.js)|Medium|
+1453|[Maximum Number of Darts Inside of a Circular Dartboard](./solutions/1453-maximum-number-of-darts-inside-of-a-circular-dartboard.js)|Hard|
 1455|[Check If a Word Occurs As a Prefix of Any Word in a Sentence](./solutions/1455-check-if-a-word-occurs-as-a-prefix-of-any-word-in-a-sentence.js)|Easy|
 1456|[Maximum Number of Vowels in a Substring of Given Length](./solutions/1456-maximum-number-of-vowels-in-a-substring-of-given-length.js)|Medium|
 1460|[Make Two Arrays Equal by Reversing Sub-arrays](./solutions/1460-make-two-arrays-equal-by-reversing-sub-arrays.js)|Easy|

solutions/1453-maximum-number-of-darts-inside-of-a-circular-dartboard.js

@@ -0,0 +1,71 @@
+/**
+ * 1453. Maximum Number of Darts Inside of a Circular Dartboard
+ * https://leetcode.com/problems/maximum-number-of-darts-inside-of-a-circular-dartboard/
+ * Difficulty: Hard
+ *
+ * Alice is throwing n darts on a very large wall. You are given an array darts where
+ * darts[i] = [xi, yi] is the position of the ith dart that Alice threw on the wall.
+ *
+ * Bob knows the positions of the n darts on the wall. He wants to place a dartboard of
+ * radius r on the wall so that the maximum number of darts that Alice throws lie on the
+ * dartboard.
+ *
+ * Given the integer r, return the maximum number of darts that can lie on the dartboard.
+ */
+
+/**
+ * @param {number[][]} darts
+ * @param {number} r
+ * @return {number}
+ */
+var numPoints = function(darts, r) {
+  let maxDarts = 1;
+  const n = darts.length;
+  const radiusSquared = r * r;
+
+  for (let i = 0; i < n; i++) {
+    for (let j = i + 1; j < n; j++) {
+      const dx = darts[j][0] - darts[i][0];
+      const dy = darts[j][1] - darts[i][1];
+      const distSquared = dx * dx + dy * dy;
+
+      if (distSquared > 4 * radiusSquared + 1e-8) continue;
+
+      const midX = (darts[i][0] + darts[j][0]) / 2;
+      const midY = (darts[i][1] + darts[j][1]) / 2;
+
+      if (distSquared < 1e-8) continue;
+
+      const dist = Math.sqrt(distSquared) / 2;
+      const height = Math.sqrt(radiusSquared - dist * dist);
+
+      let perpX = -dy;
+      let perpY = dx;
+      const norm = Math.sqrt(perpX * perpX + perpY * perpY);
+      perpX /= norm;
+      perpY /= norm;
+
+      const count1 = countDartsInCircle(darts, midX + height * perpX, midY + height * perpY, r);
+      const count2 = countDartsInCircle(darts, midX - height * perpX, midY - height * perpY, r);
+
+      maxDarts = Math.max(maxDarts, count1, count2);
+    }
+  }
+
+  return maxDarts;
+
+  function countDartsInCircle(darts, centerX, centerY, r) {
+    let count = 0;
+    const radiusSquared = r * r;
+
+    for (const dart of darts) {
+      const dx = dart[0] - centerX;
+      const dy = dart[1] - centerY;
+      if (dx * dx + dy * dy <= radiusSquared + 1e-8) {
+        count++;
+      }
+    }
+
+    return count;
+  }
+};