Add solution #754

Author: JoshCrozier

README.md

@@ -572,6 +572,7 @@
 749|[Contain Virus](./0749-contain-virus.js)|Hard|
 752|[Open the Lock](./0752-open-the-lock.js)|Medium|
 753|[Cracking the Safe](./0753-cracking-the-safe.js)|Hard|
+754|[Reach a Number](./0754-reach-a-number.js)|Medium|
 762|[Prime Number of Set Bits in Binary Representation](./0762-prime-number-of-set-bits-in-binary-representation.js)|Easy|
 763|[Partition Labels](./0763-partition-labels.js)|Medium|
 783|[Minimum Distance Between BST Nodes](./0783-minimum-distance-between-bst-nodes.js)|Easy|

solutions/0754-reach-a-number.js

@@ -0,0 +1,31 @@
+/**
+ * 754. Reach a Number
+ * https://leetcode.com/problems/reach-a-number/
+ * Difficulty: Medium
+ *
+ * You are standing at position 0 on an infinite number line. There is a destination at
+ * position target.
+ *
+ * You can make some number of moves numMoves so that:
+ * - On each move, you can either go left or right.
+ * - During the ith move (starting from i == 1 to i == numMoves), you take i steps in the
+ *   chosen direction.
+ *
+ * Given the integer target, return the minimum number of moves required (i.e., the minimum
+ * numMoves) to reach the destination.
+ */
+
+/**
+ * @param {number} target
+ * @return {number}
+ */
+var reachNumber = function(target) {
+  const absTarget = Math.abs(target);
+  let moves = Math.floor(Math.sqrt(2 * absTarget));
+
+  while (true) {
+    const sum = moves * (moves + 1) / 2;
+    if (sum >= absTarget && (sum - absTarget) % 2 === 0) return moves;
+    moves++;
+  }
+};