#261 Course Schedule

Author: forest000014

course-schedule/forest000014.java

@@ -0,0 +1,39 @@
+/*
+# Time Complexity: O(n)
+# Space Complexity: O(n)
+위상 정렬을 사용해서 풀었습니다.
+*/
+
+class Solution {
+    public boolean canFinish(int numCourses, int[][] prerequisites) {
+        int[] inDegree = new int[numCourses];
+        Queue<Integer> queue = new LinkedList<>();
+        List<List<Integer>> graph = new ArrayList<>();
+        for (int i = 0; i < numCourses; i++) {
+            graph.add(new ArrayList<>());
+        }
+
+        for (int i = 0; i < prerequisites.length; i++) {
+            graph.get(prerequisites[i][1]).add(prerequisites[i][0]);
+            inDegree[prerequisites[i][0]]++;
+        }
+
+        for (int i = 0; i < numCourses; i++) {
+            if (inDegree[i] == 0) queue.offer(i);
+        }
+
+        while (!queue.isEmpty()) {
+            int curr = queue.poll();
+
+            for (int next : graph.get(curr)) {
+                inDegree[next]--;
+                if (inDegree[next] == 0) queue.offer(next);
+            }
+        }
+
+        for (int i = 0; i < numCourses; i++) {
+            if (inDegree[i] > 0) return false;
+        }
+        return true;
+    }
+}