diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 5c9ec92..b6f8206 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -336,3 +336,5 @@ mod p3233_find_the_count_of_numbers_which_are_not_special;
 mod p3238_find_the_number_of_winning_players;
 
 mod p632_smallest_range_covering_elements_from_k_lists;
+
+mod p3206_alternating_groups_i;
diff --git a/src/problem/p3206_alternating_groups_i.rs b/src/problem/p3206_alternating_groups_i.rs
new file mode 100644
index 0000000..cf2f1c4
--- /dev/null
+++ b/src/problem/p3206_alternating_groups_i.rs
@@ -0,0 +1,42 @@
+/**
+ * [3206] Alternating Groups I
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn number_of_alternating_groups(colors: Vec<i32>) -> i32 {
+        let n = colors.len();
+
+        let mut result = 0;
+
+        for i in n..2 * n {
+            let left = (i - 1) % n;
+            let middle = i % n;
+            let right = (i + 1) % n;
+
+            if colors[left] != colors[middle] && colors[right] != colors[middle] {
+                result += 1;
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3206() {
+        assert_eq!(0, Solution::number_of_alternating_groups(vec![0, 0, 0]));
+        assert_eq!(
+            3,
+            Solution::number_of_alternating_groups(vec![0, 1, 0, 0, 1])
+        );
+    }
+}