Time: 4 ms (91.62%), Space: 45.4 MB (77.67%) - LeetHub

0210-course-schedule-ii/0210-course-schedule-ii.java

@@ -0,0 +1,41 @@
+class Solution {
+    public boolean dfs(int i,List<List<Integer>> adj,boolean[] vis,boolean[] path,Stack<Integer> st)
+    {
+        vis[i]=true;
+        path[i]=true;
+        for(int x:adj.get(i)){
+            if(!vis[x])
+            {if(dfs(x,adj,vis,path,st))
+            return true;
+            }
+            else if(path[x])
+            return true;
+        }
+        path[i]=false;
+        st.push(i);
+        return false;
+    }
+
+    public int[] findOrder(int n, int[][] pre) {
+        List<List<Integer>> adj=new ArrayList<>();
+        boolean vis[]=new boolean[n];
+        boolean path[]=new boolean[n];
+        Stack<Integer> st=new Stack<>();
+        int[] ans=new int[n];
+        for(int i=0;i<n;i++)
+            adj.add(new ArrayList<>());
+        for(int i=0;i<pre.length;i++)
+        adj.get(pre[i][1]).add(pre[i][0]);
+
+        for(int i=0;i<n;i++){
+            if(!vis[i]){
+                if(dfs(i,adj,vis,path,st))
+                return new int[0];
+            }
+        }
+        int i=0;
+        while(!st.isEmpty())
+            ans[i++]=st.pop();
+            return ans;
+    }
+}