diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index ddbbab3..294f26c 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -408,3 +408,5 @@ mod p3219_minimum_cost_for_cutting_cake_ii;
 mod p3280_convert_date_to_binary;
 
 mod p729_my_calendar_i;
+
+mod p731_my_calendar_ii;
diff --git a/src/problem/p731_my_calendar_ii.rs b/src/problem/p731_my_calendar_ii.rs
new file mode 100644
index 0000000..5656e7d
--- /dev/null
+++ b/src/problem/p731_my_calendar_ii.rs
@@ -0,0 +1,84 @@
+/**
+ * [731] My Calendar II
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::BTreeMap;
+
+struct MyCalendarTwo {
+    map: BTreeMap<i32, i32>,
+}
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl MyCalendarTwo {
+    fn new() -> Self {
+        Self {
+            map: BTreeMap::new(),
+        }
+    }
+
+    fn book(&mut self, start_time: i32, end_time: i32) -> bool {
+        let mut max_book = 0;
+
+        let start = self.map.entry(start_time).or_insert(0);
+        *start += 1;
+        let end = self.map.entry(end_time).or_insert(0);
+        *end -= 1;
+
+        for (_, &freq) in self.map.iter() {
+            max_book += freq;
+
+            if max_book > 2 {
+                let start = self.map.entry(start_time).or_insert(0);
+                *start -= 1;
+                let end = self.map.entry(end_time).or_insert(0);
+                *end += 1;
+                return false;
+            }
+        }
+
+        true
+    }
+}
+
+/**
+ * Your MyCalendarTwo object will be instantiated and called as such:
+ * let obj = MyCalendarTwo::new();
+ * let ret_1: bool = obj.book(startTime, endTime);
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_731() {
+        let mut calendar = MyCalendarTwo::new();
+
+        assert!(calendar.book(24, 40));
+        assert!(calendar.book(43, 50));
+        assert!(calendar.book(27, 43));
+        assert!(calendar.book(5, 21));
+        assert!(!calendar.book(30, 40));
+        assert!(!calendar.book(14, 29));
+        assert!(calendar.book(3, 19));
+        assert!(!calendar.book(3, 14));
+        assert!(!calendar.book(25, 39));
+        assert!(!calendar.book(6, 19));
+
+        let mut calendar = MyCalendarTwo::new();
+
+        assert!(calendar.book(10, 20));
+        assert!(calendar.book(50, 60));
+        assert!(calendar.book(10, 40));
+        assert!(!calendar.book(5, 15));
+        assert!(calendar.book(5, 10));
+        assert!(calendar.book(25, 55));
+    }
+}