Add solution #149

Author: JoshCrozier

README.md

@@ -88,6 +88,7 @@
 143|[Reorder List](./0143-reorder-list.js)|Medium|
 144|[Binary Tree Preorder Traversal](./0144-binary-tree-preorder-traversal.js)|Easy|
 145|[Binary Tree Postorder Traversal](./0145-binary-tree-postorder-traversal.js)|Easy|
+149|[Max Points on a Line](./0149-max-points-on-a-line.js)|Hard|
 151|[Reverse Words in a String](./0151-reverse-words-in-a-string.js)|Medium|
 152|[Maximum Product Subarray](./0152-maximum-product-subarray.js)|Medium|
 167|[Two Sum II - Input Array Is Sorted](./0167-two-sum-ii-input-array-is-sorted.js)|Easy|

solutions/0149-max-points-on-a-line.js

@@ -0,0 +1,29 @@
+/**
+ * 149. Max Points on a Line
+ * https://leetcode.com/problems/max-points-on-a-line/
+ * Difficulty: Hard
+ *
+ * Given an array of points where points[i] = [xi, yi] represents a point on the X-Y plane,
+ * return the maximum number of points that lie on the same straight line.
+ */
+
+/**
+ * @param {number[][]} points
+ * @return {number}
+ */
+var maxPoints = function(points) {
+  let max = 0;
+
+  points.forEach(x => {
+    const slopes = new Map();
+
+    points.forEach(y => {
+      if (x === y) return;
+      const slope = y[0] - x[0] !== 0 ? (y[1] - x[1]) / (y[0] - x[0]) : Infinity;
+      slopes.set(slope, (slopes.get(slope) || 0) + 1);
+      max = Math.max(max, slopes.get(slope));
+    });
+  });
+
+  return max + 1;
+};