Add solution #1557

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,365 LeetCode solutions in JavaScript
+# 1,366 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1188,6 +1188,7 @@
 1552|[Magnetic Force Between Two Balls](./solutions/1552-magnetic-force-between-two-balls.js)|Medium|
 1553|[Minimum Number of Days to Eat N Oranges](./solutions/1553-minimum-number-of-days-to-eat-n-oranges.js)|Hard|
 1556|[Thousand Separator](./solutions/1556-thousand-separator.js)|Easy|
+1557|[Minimum Number of Vertices to Reach All Nodes](./solutions/1557-minimum-number-of-vertices-to-reach-all-nodes.js)|Medium|
 1566|[Detect Pattern of Length M Repeated K or More Times](./solutions/1566-detect-pattern-of-length-m-repeated-k-or-more-times.js)|Easy|
 1576|[Replace All ?'s to Avoid Consecutive Repeating Characters](./solutions/1576-replace-all-s-to-avoid-consecutive-repeating-characters.js)|Medium|
 1598|[Crawler Log Folder](./solutions/1598-crawler-log-folder.js)|Easy|

solutions/1557-minimum-number-of-vertices-to-reach-all-nodes.js

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+/**
+ * 1557. Minimum Number of Vertices to Reach All Nodes
+ * https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes/
+ * Difficulty: Medium
+ *
+ * Given a directed acyclic graph, with n vertices numbered from 0 to n-1, and an array edges
+ * where edges[i] = [fromi, toi] represents a directed edge from node fromi to node toi.
+ *
+ * Find the smallest set of vertices from which all nodes in the graph are reachable. It's
+ * guaranteed that a unique solution exists.
+ *
+ * Notice that you can return the vertices in any order.
+ */
+
+/**
+ * @param {number} n
+ * @param {number[][]} edges
+ * @return {number[]}
+ */
+var findSmallestSetOfVertices = function(n, edges) {
+  const hasIncomingEdge = new Array(n).fill(false);
+  for (const [_, to] of edges) {
+    hasIncomingEdge[to] = true;
+  }
+
+  const result = [];
+  for (let i = 0; i < n; i++) {
+    if (!hasIncomingEdge[i]) {
+      result.push(i);
+    }
+  }
+
+  return result;
+};