20241114 finished.

src/problem/mod.rs

@@ -314,3 +314,5 @@ mod p1547_minimum_cost_to_cut_a_stick;
 mod p3258_count_substrings_that_satisfy_k_constraint_i;
 
 mod p3261_count_substrings_that_satisfy_k_constraint_ii;
+
+mod p3249_count_the_number_of_good_nodes;

src/problem/p3249_count_the_number_of_good_nodes.rs

@@ -0,0 +1,97 @@
+/**
+ * [3249] Count the Number of Good Nodes
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn count_good_nodes(edges: Vec<Vec<i32>>) -> i32 {
+        let n = edges.len() + 1;
+        let mut matrix = vec![vec![]; n];
+
+        edges
+            .into_iter()
+            .map(|edge| (edge[0] as usize, edge[1] as usize))
+            .for_each(|(x, y)| {
+                matrix[x].push(y);
+                matrix[y].push(x);
+            });
+
+        let mut result = 0;
+        Self::dfs(&matrix, 0, usize::MAX, &mut result);
+        result
+    }
+
+    fn dfs(tree: &Vec<Vec<usize>>, node: usize, parent: usize, result: &mut i32) -> i32 {
+        if tree[node].len() == 0 {
+            *result += 1;
+            return 1;
+        }
+
+        let children: Vec<i32> = tree[node]
+            .iter()
+            .filter_map(|&child| {
+                if child == parent {
+                    None
+                } else {
+                    Some(Self::dfs(tree, child, node, result))
+                }
+            })
+            .collect();
+
+        if children.iter().all(|x| *x == children[0]) {
+            *result += 1;
+        }
+
+        children.into_iter().sum::<i32>() + 1
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3249() {
+        assert_eq!(
+            7,
+            Solution::count_good_nodes(vec![
+                vec![0, 1],
+                vec![0, 2],
+                vec![1, 3],
+                vec![1, 4],
+                vec![2, 5],
+                vec![2, 6]
+            ])
+        );
+
+        assert_eq!(
+            6,
+            Solution::count_good_nodes(vec![
+                vec![0, 1],
+                vec![1, 2],
+                vec![2, 3],
+                vec![3, 4],
+                vec![0, 5],
+                vec![1, 6],
+                vec![2, 7],
+                vec![3, 8]
+            ])
+        );
+
+        assert_eq!(
+            6,
+            Solution::count_good_nodes(vec![
+                vec![6, 0],
+                vec![1, 0],
+                vec![5, 1],
+                vec![2, 5],
+                vec![3, 1],
+                vec![4, 3]
+            ])
+        );
+    }
+}