20240624 Finished

src/problem/mod.rs

@@ -156,4 +156,5 @@ mod p230_kth_smallest_element_in_a_bst;
 mod p98_validate_binary_search_tree;
 mod p200_number_of_islands;
 mod p130_surrounded_regions;
-mod p399_evaluate_division;
+mod p399_evaluate_division;
+mod p207_course_schedule;

src/problem/p207_course_schedule.rs

@@ -0,0 +1,56 @@
+/**
+ * [207] Course Schedule
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+use std::collections::VecDeque;
+
+impl Solution {
+    pub fn can_finish(num_courses: i32, prerequisites: Vec<Vec<i32>>) -> bool {
+        let num_courses = num_courses as usize;
+        let mut edges = vec![vec![];num_courses];
+        let mut in_degs = vec![0;num_courses];
+
+        for edge in prerequisites {
+            edges[edge[1] as usize].push(edge[0] as usize);
+            in_degs[edge[0] as usize] += 1;
+        }
+
+        let mut queue = VecDeque::new();
+
+        for i in 0..num_courses {
+            if in_degs[i] == 0 {
+                queue.push_back(i);
+            }
+        } 
+
+        let mut visited = 0;
+        while !queue.is_empty() {
+            let node = queue.pop_front().unwrap(); 
+            visited += 1;
+
+            for next_node in &edges[node] {
+                in_degs[*next_node] -= 1;
+                
+                if in_degs[*next_node] == 0 {
+                    queue.push_back(*next_node);
+                }
+            }            
+        }
+
+        visited == num_courses
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_207() {
+    }
+}