Add solution #1130

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,145 LeetCode solutions in JavaScript
+# 1,146 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -891,6 +891,7 @@
 1125|[Smallest Sufficient Team](./solutions/1125-smallest-sufficient-team.js)|Hard|
 1128|[Number of Equivalent Domino Pairs](./solutions/1128-number-of-equivalent-domino-pairs.js)|Easy|
 1129|[Shortest Path with Alternating Colors](./solutions/1129-shortest-path-with-alternating-colors.js)|Medium|
+1130|[Minimum Cost Tree From Leaf Values](./solutions/1130-minimum-cost-tree-from-leaf-values.js)|Medium|
 1137|[N-th Tribonacci Number](./solutions/1137-n-th-tribonacci-number.js)|Easy|
 1143|[Longest Common Subsequence](./solutions/1143-longest-common-subsequence.js)|Medium|
 1161|[Maximum Level Sum of a Binary Tree](./solutions/1161-maximum-level-sum-of-a-binary-tree.js)|Medium|

solutions/1130-minimum-cost-tree-from-leaf-values.js

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+/**
+ * 1130. Minimum Cost Tree From Leaf Values
+ * https://leetcode.com/problems/minimum-cost-tree-from-leaf-values/
+ * Difficulty: Medium
+ *
+ * Given an array arr of positive integers, consider all binary trees such that:
+ * - Each node has either 0 or 2 children;
+ * - The values of arr correspond to the values of each leaf in an in-order traversal of the tree.
+ * - The value of each non-leaf node is equal to the product of the largest leaf value in its left
+ *   and right subtree, respectively.
+ *
+ * Among all possible binary trees considered, return the smallest possible sum of the values of
+ * each non-leaf node. It is guaranteed this sum fits into a 32-bit integer.
+ *
+ * A node is a leaf if and only if it has zero children.
+ */
+
+/**
+ * @param {number[]} arr
+ * @return {number}
+ */
+var mctFromLeafValues = function(arr) {
+  const stack = [];
+  let result = 0;
+
+  for (const value of arr) {
+    while (stack.length && stack[stack.length - 1] <= value) {
+      const small = stack.pop();
+      result += small * Math.min(stack[stack.length - 1] || Infinity, value);
+    }
+    stack.push(value);
+  }
+
+  while (stack.length > 1) {
+    const small = stack.pop();
+    result += small * stack[stack.length - 1];
+  }
+
+  return result;
+};