Add solution #1687

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,474 LeetCode solutions in JavaScript
+# 1,475 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1299,6 +1299,7 @@
 1684|[Count the Number of Consistent Strings](./solutions/1684-count-the-number-of-consistent-strings.js)|Easy|
 1685|[Sum of Absolute Differences in a Sorted Array](./solutions/1685-sum-of-absolute-differences-in-a-sorted-array.js)|Medium|
 1686|[Stone Game VI](./solutions/1686-stone-game-vi.js)|Medium|
+1687|[Delivering Boxes from Storage to Ports](./solutions/1687-delivering-boxes-from-storage-to-ports.js)|Hard|
 1716|[Calculate Money in Leetcode Bank](./solutions/1716-calculate-money-in-leetcode-bank.js)|Easy|
 1718|[Construct the Lexicographically Largest Valid Sequence](./solutions/1718-construct-the-lexicographically-largest-valid-sequence.js)|Medium|
 1726|[Tuple with Same Product](./solutions/1726-tuple-with-same-product.js)|Medium|

solutions/1687-delivering-boxes-from-storage-to-ports.js

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+/**
+ * 1687. Delivering Boxes from Storage to Ports
+ * https://leetcode.com/problems/delivering-boxes-from-storage-to-ports/
+ * Difficulty: Hard
+ *
+ * You have the task of delivering some boxes from storage to their ports using only one ship.
+ * However, this ship has a limit on the number of boxes and the total weight that it can carry.
+ *
+ * You are given an array boxes, where boxes[i] = [portsi, weighti], and three integers
+ * portsCount, maxBoxes, and maxWeight.
+ * - portsi is the port where you need to deliver the ith box and weightsi is the weight of
+ *   the ith box.
+ * - portsCount is the number of ports.
+ * - maxBoxes and maxWeight are the respective box and weight limits of the ship.
+ *
+ * The boxes need to be delivered in the order they are given. The ship will follow these steps:
+ * - The ship will take some number of boxes from the boxes queue, not violating the maxBoxes and
+ *   maxWeight constraints.
+ * - For each loaded box in order, the ship will make a trip to the port the box needs to be
+ *   delivered to and deliver it. If the ship is already at the correct port, no trip is needed,
+ *   and the box can immediately be delivered.
+ * - The ship then makes a return trip to storage to take more boxes from the queue.
+ *
+ * The ship must end at storage after all the boxes have been delivered.
+ *
+ * Return the minimum number of trips the ship needs to make to deliver all boxes to their
+ * respective ports.
+ */
+
+/**
+ * @param {number[][]} boxes
+ * @param {number} portsCount
+ * @param {number} maxBoxes
+ * @param {number} maxWeight
+ * @return {number}
+ */
+var boxDelivering = function(boxes, portsCount, maxBoxes, maxWeight) {
+  const n = boxes.length;
+  const minTrips = new Array(n + 1).fill(0);
+  let start = 0;
+  let portChanges = 0;
+
+  for (let end = 0; end < n; end++) {
+    maxBoxes--;
+    maxWeight -= boxes[end][1];
+    if (end > 0 && boxes[end][0] !== boxes[end - 1][0]) portChanges++;
+
+    while (maxBoxes < 0 || maxWeight < 0
+          || (start < end && minTrips[start + 1] === minTrips[start])) {
+      maxBoxes++;
+      maxWeight += boxes[start++][1];
+      if (start > 0 && boxes[start][0] !== boxes[start - 1][0]) portChanges--;
+    }
+
+    minTrips[end + 1] = portChanges + 2 + minTrips[start];
+  }
+
+  return minTrips[n];
+};