Add solution #321

Author: JoshCrozier

README.md

@@ -259,6 +259,7 @@
 316|[Remove Duplicate Letters](./0316-remove-duplicate-letters.js)|Medium|
 318|[Maximum Product of Word Lengths](./0318-maximum-product-of-word-lengths.js)|Medium|
 319|[Bulb Switcher](./0319-bulb-switcher.js)|Medium|
+321|[Create Maximum Number](./0321-create-maximum-number.js)|Hard|
 322|[Coin Change](./0322-coin-change.js)|Medium|
 324|[Wiggle Sort II](./0324-wiggle-sort-ii.js)|Medium|
 326|[Power of Three](./0326-power-of-three.js)|Easy|

solutions/0321-create-maximum-number.js

@@ -0,0 +1,63 @@
+/**
+ * 321. Create Maximum Number
+ * https://leetcode.com/problems/create-maximum-number/
+ * Difficulty: Hard
+ *
+ * You are given two integer arrays nums1 and nums2 of lengths m and n respectively.
+ * nums1 and nums2 represent the digits of two numbers. You are also given an integer k.
+ *
+ * Create the maximum number of length k <= m + n from digits of the two numbers. The
+ * relative order of the digits from the same array must be preserved.
+ *
+ * Return an array of the k digits representing the answer.
+ */
+
+/**
+ * @param {number[]} nums1
+ * @param {number[]} nums2
+ * @param {number} k
+ * @return {number[]}
+ */
+var maxNumber = function(nums1, nums2, k) {
+  const m = nums1.length;
+  const n = nums2.length;
+  let result = new Array(k).fill(0);
+
+  for (let i = Math.max(0, k - n); i <= Math.min(k, m); i++) {
+    if (i + n < k) continue;
+    const candidate = merge(
+      getMaxSubsequence(nums1, i),
+      getMaxSubsequence(nums2, k - i),
+    );
+    result = candidate > result ? candidate : result;
+  }
+
+  return result;
+
+  function getMaxSubsequence(nums, count) {
+    const stack = [];
+    let removeIndex = nums.length - count;
+
+    nums.forEach(n => {
+      while (stack.length && stack[stack.length - 1] < n && removeIndex) {
+        stack.pop();
+        removeIndex--;
+      }
+      stack.push(n);
+    });
+
+    return stack.slice(0, count);
+  }
+
+  function merge(a1, a2) {
+    const result = [];
+
+    while (a1.length || a2.length) {
+      const compare = a1 > a2 ? a1 : a2;
+      result.push(compare[0]);
+      compare.shift();
+    }
+
+    return result;
+  }
+};