3. Course Schedule

Author: Sunjae95

course-schedule/sunjae95.js

@@ -0,0 +1,47 @@
+/**
+ * @description
+ * memoization + dfs
+ *
+ * n = length of nums
+ * p = length of prerequisites
+ *
+ * time complexity: O(n)
+ * space complexity: O(p)
+ */
+var canFinish = function (numCourses, prerequisites) {
+  const memo = Array.from({ length: numCourses + 1 }, () => false);
+  const visited = Array.from({ length: numCourses + 1 }, () => false);
+  // graph setting
+  const graph = prerequisites.reduce((map, [linkedNode, current]) => {
+    const list = map.get(current) ?? [];
+    list.push(linkedNode);
+    map.set(current, list);
+    return map;
+  }, new Map());
+
+  const dfs = (current) => {
+    const linkedNode = graph.get(current);
+
+    if (memo[current] || !linkedNode || linkedNode.length === 0) return true;
+
+    for (const node of linkedNode) {
+      if (visited[node]) return false;
+
+      visited[node] = true;
+      if (!dfs(node)) return false;
+      visited[node] = false;
+      memo[node] = true;
+    }
+
+    return true;
+  };
+
+  for (const [current] of graph) {
+    visited[current] = true;
+    if (!dfs(current)) return false;
+    visited[current] = false;
+    memo[current] = true;
+  }
+
+  return true;
+};