Add solution #2028

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,695 LeetCode solutions in JavaScript
+# 1,696 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1555,6 +1555,7 @@
 2024|[Maximize the Confusion of an Exam](./solutions/2024-maximize-the-confusion-of-an-exam.js)|Medium|
 2025|[Maximum Number of Ways to Partition an Array](./solutions/2025-maximum-number-of-ways-to-partition-an-array.js)|Hard|
 2027|[Minimum Moves to Convert String](./solutions/2027-minimum-moves-to-convert-string.js)|Easy|
+2028|[Find Missing Observations](./solutions/2028-find-missing-observations.js)|Medium|
 2033|[Minimum Operations to Make a Uni-Value Grid](./solutions/2033-minimum-operations-to-make-a-uni-value-grid.js)|Medium|
 2037|[Minimum Number of Moves to Seat Everyone](./solutions/2037-minimum-number-of-moves-to-seat-everyone.js)|Easy|
 2047|[Number of Valid Words in a Sentence](./solutions/2047-number-of-valid-words-in-a-sentence.js)|Easy|

solutions/2028-find-missing-observations.js

@@ -0,0 +1,49 @@
+/**
+ * 2028. Find Missing Observations
+ * https://leetcode.com/problems/find-missing-observations/
+ * Difficulty: Medium
+ *
+ * You have observations of n + m 6-sided dice rolls with each face numbered from 1 to 6. n
+ * of the observations went missing, and you only have the observations of m rolls.
+ * Fortunately, you have also calculated the average value of the n + m rolls.
+ *
+ * You are given an integer array rolls of length m where rolls[i] is the value of the ith
+ * observation. You are also given the two integers mean and n.
+ *
+ * Return an array of length n containing the missing observations such that the average
+ * value of the n + m rolls is exactly mean. If there are multiple valid answers, return
+ * any of them. If no such array exists, return an empty array.
+ *
+ * The average value of a set of k numbers is the sum of the numbers divided by k.
+ *
+ * Note that mean is an integer, so the sum of the n + m rolls should be divisible by n + m.
+ */
+
+/**
+ * @param {number[]} rolls
+ * @param {number} mean
+ * @param {number} n
+ * @return {number[]}
+ */
+var missingRolls = function(rolls, mean, n) {
+  const totalRolls = rolls.length + n;
+  const targetSum = mean * totalRolls;
+  const currentSum = rolls.reduce((sum, roll) => sum + roll, 0);
+  const missingSum = targetSum - currentSum;
+
+  if (missingSum < n || missingSum > 6 * n) return [];
+
+  const baseValue = Math.floor(missingSum / n);
+  const remainder = missingSum % n;
+  const result = [];
+
+  for (let i = 0; i < n; i++) {
+    if (i < remainder) {
+      result.push(baseValue + 1);
+    } else {
+      result.push(baseValue);
+    }
+  }
+
+  return result;
+};