Add solution #780

Author: JoshCrozier

README.md

@@ -590,6 +590,7 @@
 777|[Swap Adjacent in LR String](./0777-swap-adjacent-in-lr-string.js)|Medium|
 778|[Swim in Rising Water](./0778-swim-in-rising-water.js)|Hard|
 779|[K-th Symbol in Grammar](./0779-k-th-symbol-in-grammar.js)|Medium|
+780|[Reaching Points](./0780-reaching-points.js)|Hard|
 783|[Minimum Distance Between BST Nodes](./0783-minimum-distance-between-bst-nodes.js)|Easy|
 784|[Letter Case Permutation](./0784-letter-case-permutation.js)|Medium|
 790|[Domino and Tromino Tiling](./0790-domino-and-tromino-tiling.js)|Medium|

solutions/0780-reaching-points.js

@@ -0,0 +1,41 @@
+/**
+ * 780. Reaching Points
+ * https://leetcode.com/problems/reaching-points/
+ * Difficulty: Hard
+ *
+ * Given four integers sx, sy, tx, and ty, return true if it is possible to convert the point
+ * (sx, sy) to the point (tx, ty) through some operations, or false otherwise.
+ *
+ * The allowed operation on some point (x, y) is to convert it to either (x, x + y) or (x + y, y).
+ */
+
+/**
+ * @param {number} sx
+ * @param {number} sy
+ * @param {number} tx
+ * @param {number} ty
+ * @return {boolean}
+ */
+var reachingPoints = function(sx, sy, tx, ty) {
+  while (tx >= sx && ty >= sy) {
+    if (tx === sx && ty === sy) {
+      return true;
+    }
+
+    if (tx > ty) {
+      // If we can directly reach sx by making proper subtractions
+      if (ty === sy) {
+        return (tx - sx) % ty === 0;
+      }
+      tx %= ty;
+    } else {
+      // If we can directly reach sy by making proper subtractions
+      if (tx === sx) {
+        return (ty - sy) % tx === 0;
+      }
+      ty %= tx;
+    }
+  }
+
+  return false;
+};