Add solution #421

Author: JoshCrozier

0421-maximum-xor-of-two-numbers-in-an-array.js

@@ -0,0 +1,30 @@
+/**
+ * 421. Maximum XOR of Two Numbers in an Array
+ * https://leetcode.com/problems/maximum-xor-of-two-numbers-in-an-array/
+ * Difficulty: Medium
+ *
+ * Given an integer array nums, return the maximum result of nums[i] XOR
+ * nums[j], where 0 <= i <= j < n.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var findMaximumXOR = function(nums) {
+  let result = 0;
+
+  for (let i = 31, mask = 0; i >= 0; i--) {
+    mask |= (1 << i);
+    const set = new Set(nums.map(num => num & mask));
+    const target = result | (1 << i);
+    for (const prefix of set) {
+      if (set.has(prefix ^ target)) {
+        result = target;
+        break;
+      }
+    }
+  }
+
+  return result;
+};

README.md

@@ -336,6 +336,7 @@
 417|[Pacific Atlantic Water Flow](./0417-pacific-atlantic-water-flow.js)|Medium|
 419|[Battleships in a Board](./0419-battleships-in-a-board.js)|Medium|
 420|[Strong Password Checker](./0420-strong-password-checker.js)|Hard|
+421|[Maximum XOR of Two Numbers in an Array](./0421-maximum-xor-of-two-numbers-in-an-array.js)|Medium|
 434|[Number of Segments in a String](./0434-number-of-segments-in-a-string.js)|Easy|
 435|[Non-overlapping Intervals](./0435-non-overlapping-intervals.js)|Medium|
 437|[Path Sum III](./0437-path-sum-iii.js)|Medium|