Add solution #356

Author: JoshCrozier

README.md

@@ -344,6 +344,7 @@
 353|[Design Snake Game](./solutions/0353-design-snake-game.js)|Medium|
 354|[Russian Doll Envelopes](./solutions/0354-russian-doll-envelopes.js)|Hard|
 355|[Design Twitter](./solutions/0355-design-twitter.js)|Medium|
+356|[Line Reflection](./solutions/0356-line-reflection.js)|Medium|
 357|[Count Numbers with Unique Digits](./solutions/0357-count-numbers-with-unique-digits.js)|Medium|
 363|[Max Sum of Rectangle No Larger Than K](./solutions/0363-max-sum-of-rectangle-no-larger-than-k.js)|Hard|
 365|[Water and Jug Problem](./solutions/0365-water-and-jug-problem.js)|Medium|

solutions/0356-line-reflection.js

@@ -0,0 +1,37 @@
+/**
+ * 356. Line Reflection
+ * https://leetcode.com/problems/line-reflection/
+ * Difficulty: Medium
+ *
+ * Given n points on a 2D plane, find if there is such a line parallel to the y-axis that reflects
+ * the given points symmetrically.
+ *
+ * In other words, answer whether or not if there exists a line that after reflecting all points
+ * over the given line, the original points' set is the same as the reflected ones.
+ *
+ * Note that there can be repeated points.
+ */
+
+/**
+ * @param {number[][]} points
+ * @return {boolean}
+ */
+var isReflected = function(points) {
+  const pointSet = new Set(points.map(([x, y]) => `${x},${y}`));
+  let minX = Infinity;
+  let maxX = -Infinity;
+
+  for (const [x] of points) {
+    minX = Math.min(minX, x);
+    maxX = Math.max(maxX, x);
+  }
+
+  const sum = minX + maxX;
+  for (const [x, y] of points) {
+    if (!pointSet.has(`${sum - x},${y}`)) {
+      return false;
+    }
+  }
+
+  return true;
+};