update 207 java, progress

data/progress.txt

@@ -1,4 +1,4 @@
-20240609: 236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)
+20240609: 236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)
 20240608: 503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77
 20240607: 235(ok),236(again),496(ok),110(ok),1448(again!)
 20240606: 206,143,138(again),141,needcode_tree,226,104,110(again!!!)

data/to_review.txt

@@ -1,4 +1,4 @@
-2024-08-03 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)']
+2024-08-03 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)']
 2024-08-02 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77']
 2024-08-01 -> ['235(ok),236(again),496(ok),110(ok),1448(again!)']
 2024-07-31 -> ['206,143,138(again),141,needcode_tree,226,104,110(again!!!)']
@@ -18,7 +18,7 @@
 2024-07-16 -> ['62,572,57']
 2024-07-15 -> ['322,191,190']
 2024-07-14 -> ['73,200,70,323(again)']
-2024-07-13 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '207,79,206,213,198']
+2024-07-13 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '207,79,206,213,198']
 2024-07-12 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '212(todo),211,338,208(again)']
 2024-07-11 -> ['235(ok),236(again),496(ok),110(ok),1448(again!)', '347,253(todo),91(todo),217']
 2024-07-10 -> ['206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '226,98,253(todo)']
@@ -30,27 +30,27 @@
 2024-07-04 -> ['005,003(again)', '125']
 2024-07-02 -> ['11,647,261(again),133(again)']
 2024-07-01 -> ['143,15,268,141,139']
-2024-06-30 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '21,20,19,271,269']
+2024-06-30 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '21,20,19,271,269']
 2024-06-29 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '417(again),33,153,152']
 2024-06-28 -> ['235(ok),236(again),496(ok),110(ok),1448(again!)', '424,297(todo),295(todo),39']
 2024-06-27 -> ['206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '55,54(todo),53(again),435(again),49,48(todo),300(again)']
 2024-06-26 -> ['150,22(again),739(again!!!),needcode_linkedlist', '56']
 2024-06-25 -> ['567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '62,572,57']
 2024-06-24 -> ['146,460,582(ok*),139(ok),322(todo)', '322,191,190']
 2024-06-23 -> ['127,742(again),133(again),207(ok*),261(ok)', '73,200,70,323(again)']
-2024-06-22 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '128,261', '207,79,206,213,198']
+2024-06-22 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '128,261', '207,79,206,213,198']
 2024-06-21 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '005,003(again)', '212(todo),211,338,208(again)']
 2024-06-20 -> ['235(ok),236(again),496(ok),110(ok),1448(again!)', '347,253(todo),91(todo),217']
 2024-06-19 -> ['206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '11,647,261(again),133(again)', '226,98,253(todo)']
 2024-06-18 -> ['150,22(again),739(again!!!),needcode_linkedlist', '143,15,268,141,139', '104,230,102,100']
-2024-06-17 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '21,20,19,271,269', '105,106']
+2024-06-17 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '21,20,19,271,269', '105,106']
 2024-06-16 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '146,460,582(ok*),139(ok),322(todo)', '417(again),33,153,152', '242,235']
 2024-06-15 -> ['235(ok),236(again),496(ok),110(ok),1448(again!)', '127,742(again),133(again),207(ok*),261(ok)', '424,297(todo),295(todo),39', '371']
-2024-06-14 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '128,261', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '121,252']
+2024-06-14 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '128,261', '55,54(todo),53(again),435(again),49,48(todo),300(again)', '121,252']
 2024-06-13 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '150,22(again),739(again!!!),needcode_linkedlist', '005,003(again)', '56', '125']
-2024-06-12 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '235(ok),236(again),496(ok),110(ok),1448(again!)', '567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '62,572,57']
-2024-06-11 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '146,460,582(ok*),139(ok),322(todo)', '11,647,261(again),133(again)', '322,191,190']
-2024-06-10 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo)', '503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '235(ok),236(again),496(ok),110(ok),1448(again!)', '150,22(again),739(again!!!),needcode_linkedlist', '127,742(again),133(again),207(ok*),261(ok)', '143,15,268,141,139', '73,200,70,323(again)']
+2024-06-12 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '235(ok),236(again),496(ok),110(ok),1448(again!)', '567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '62,572,57']
+2024-06-11 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '146,460,582(ok*),139(ok),322(todo)', '11,647,261(again),133(again)', '322,191,190']
+2024-06-10 -> ['236(again*),1448(again),needcode_trie,208(ok*),needcode_graph,695,22(todo),981(todo),207(todo)', '503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '235(ok),236(again),496(ok),110(ok),1448(again!)', '150,22(again),739(again!!!),needcode_linkedlist', '127,742(again),133(again),207(ok*),261(ok)', '143,15,268,141,139', '73,200,70,323(again)']
 2024-06-09 -> ['503(todo),739(ok),105(todo),needcode_heap_pq,1046,215,needcode_backtrack,78,39(todo),46,90(todo),77', '235(ok),236(again),496(ok),110(ok),1448(again!)', '206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '128,261', '21,20,19,271,269', '207,79,206,213,198']
 2024-06-08 -> ['235(ok),236(again),496(ok),110(ok),1448(again!)', '206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '150,22(again),739(again!!!),needcode_linkedlist', '146,460,582(ok*),139(ok),322(todo)', '005,003(again)', '417(again),33,153,152', '212(todo),211,338,208(again)']
 2024-06-07 -> ['206,143,138(again),141,needcode_tree,226,104,110(again!!!)', '150,22(again),739(again!!!),needcode_linkedlist', '567(todo),needcode_array_hash,needcode_sliding_window,567(again),needcode_stack,155(again)', '127,742(again),133(again),207(ok*),261(ok)', '424,297(todo),295(todo),39', '347,253(todo),91(todo),217']

leetcode_java/src/main/java/LeetCodeJava/BFS/CourseSchedule.java

@@ -9,11 +9,57 @@ public class CourseSchedule {
     // V0
     // IDEA : DFS
     // TODO : implement
+    // NOTE !!! instead of maintain status (0,1,2), below video offers a simpler approach
+    //      -> e.g. use a set, recording the current visiting course, if ANY duplicated (already in set) course being met,
+    //      -> means "cyclic", so return false directly
+    // https://www.youtube.com/watch?v=EgI5nU9etnU
 
     // VO'
     // IDEA : TOPOLOGICAL SORT
     // TODO : implement
 
+    // V0''
+    // IDEA : DFS
+    // https://github.com/neetcode-gh/leetcode/blob/main/java/0207-course-schedule.java
+    // https://www.youtube.com/watch?v=EgI5nU9etnU
+    public boolean canFinish_0_1(int numCourses, int[][] prerequisites) {
+        List<List<Integer>> adj = new ArrayList<>();
+        for (int i = 0; i < numCourses; i++) {
+            adj.add(new ArrayList<>());
+        }
+
+        for (int i = 0; i < prerequisites.length; i++) {
+            adj.get(prerequisites[i][0]).add(prerequisites[i][1]);
+        }
+
+        int[] visited = new int[numCourses];
+        for (int i = 0; i < numCourses; i++) {
+            if (visited[i] == 0) {
+                if (isCyclic(adj, visited, i)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    private boolean isCyclic(List<List<Integer>> adj, int[] visited, int curr) {
+        if (visited[curr] == 2) {
+            return true;
+        }
+
+        visited[curr] = 2;
+        for (int i = 0; i < adj.get(curr).size(); i++) {
+            if (visited[adj.get(curr).get(i)] != 1) {
+                if (isCyclic(adj, visited, adj.get(curr).get(i))) {
+                    return true;
+                }
+            }
+        }
+        visited[curr] = 1;
+        return false;
+    }
+
     // V0''
     // IDEA : DFS
     // https://github.com/yennanliu/CS_basics/blob/master/leetcode_python/Breadth-First-Search/course-schedule.py