diff --git a/solution/0700-0799/0731.My Calendar II/README.md b/solution/0700-0799/0731.My Calendar II/README.md
index 1971961290950..578746ebaf9a2 100644
--- a/solution/0700-0799/0731.My Calendar II/README.md	
+++ b/solution/0700-0799/0731.My Calendar II/README.md	
@@ -43,7 +43,7 @@ MyCalendar.book(10, 40); // returns true
 MyCalendar.book(5, 15); // returns false
 MyCalendar.book(5, 10); // returns true
 MyCalendar.book(25, 55); // returns true
-<strong>解释：</strong> 
+<strong>解释：</strong>
 前两个日程安排可以添加至日历中。 第三个日程安排会导致双重预订，但可以添加至日历中。
 第四个日程安排活动（5,15）不能添加至日历中，因为它会导致三重预订。
 第五个日程安排（5,10）可以添加至日历中，因为它未使用已经双重预订的时间10。
@@ -642,4 +642,74 @@ func (this *MyCalendarTwo) Book(start int, end int) bool {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### Solution 3: Line Sweep
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+class MyCalendarTwo {
+    #OVERLAPS = 2;
+    #cnt: Record<number, number> = {};
+
+    book(start: number, end: number): boolean {
+        this.#cnt[start] = (this.#cnt[start] ?? 0) + 1;
+        this.#cnt[end] = (this.#cnt[end] ?? 0) - 1;
+
+        let sum = 0;
+        for (const v of Object.values(this.#cnt)) {
+            sum += v;
+            if (sum > this.#OVERLAPS) {
+                this.#cnt[start]--;
+                this.#cnt[end]++;
+
+                if (!this.#cnt[start]) delete this.#cnt[start];
+                if (!this.#cnt[end]) delete this.#cnt[end];
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
+```
+
+#### JavaScript
+
+```js
+class MyCalendarTwo {
+    #OVERLAPS = 2;
+    #cnt = {};
+
+    book(start, end) {
+        this.#cnt[start] = (this.#cnt[start] ?? 0) + 1;
+        this.#cnt[end] = (this.#cnt[end] ?? 0) - 1;
+
+        let sum = 0;
+        for (const v of Object.values(this.#cnt)) {
+            sum += v;
+            if (sum > this.#OVERLAPS) {
+                this.#cnt[start]--;
+                this.#cnt[end]++;
+
+                if (!this.#cnt[start]) delete this.#cnt[start];
+                if (!this.#cnt[end]) delete this.#cnt[end];
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->
diff --git a/solution/0700-0799/0731.My Calendar II/README_EN.md b/solution/0700-0799/0731.My Calendar II/README_EN.md
index 5d3abb9bcf791..32a758cc70e09 100644
--- a/solution/0700-0799/0731.My Calendar II/README_EN.md	
+++ b/solution/0700-0799/0731.My Calendar II/README_EN.md	
@@ -46,9 +46,9 @@ tags:
 
 <strong>Explanation</strong>
 MyCalendarTwo myCalendarTwo = new MyCalendarTwo();
-myCalendarTwo.book(10, 20); // return True, The event can be booked. 
-myCalendarTwo.book(50, 60); // return True, The event can be booked. 
-myCalendarTwo.book(10, 40); // return True, The event can be double booked. 
+myCalendarTwo.book(10, 20); // return True, The event can be booked.
+myCalendarTwo.book(50, 60); // return True, The event can be booked.
+myCalendarTwo.book(10, 40); // return True, The event can be double booked.
 myCalendarTwo.book(5, 15);  // return False, The event cannot be booked, because it would result in a triple booking.
 myCalendarTwo.book(5, 10); // return True, The event can be booked, as it does not use time 10 which is already double booked.
 myCalendarTwo.book(25, 55); // return True, The event can be booked, as the time in [25, 40) will be double booked with the third event, the time [40, 50) will be single booked, and the time [50, 55) will be double booked with the second event.
@@ -624,4 +624,74 @@ func (this *MyCalendarTwo) Book(start int, end int) bool {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### Solution 3: Line Sweep
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+class MyCalendarTwo {
+    #OVERLAPS = 2;
+    #cnt: Record<number, number> = {};
+
+    book(start: number, end: number): boolean {
+        this.#cnt[start] = (this.#cnt[start] ?? 0) + 1;
+        this.#cnt[end] = (this.#cnt[end] ?? 0) - 1;
+
+        let sum = 0;
+        for (const v of Object.values(this.#cnt)) {
+            sum += v;
+            if (sum > this.#OVERLAPS) {
+                this.#cnt[start]--;
+                this.#cnt[end]++;
+
+                if (!this.#cnt[start]) delete this.#cnt[start];
+                if (!this.#cnt[end]) delete this.#cnt[end];
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
+```
+
+#### JavaScript
+
+```js
+class MyCalendarTwo {
+    #OVERLAPS = 2;
+    #cnt = {};
+
+    book(start, end) {
+        this.#cnt[start] = (this.#cnt[start] ?? 0) + 1;
+        this.#cnt[end] = (this.#cnt[end] ?? 0) - 1;
+
+        let sum = 0;
+        for (const v of Object.values(this.#cnt)) {
+            sum += v;
+            if (sum > this.#OVERLAPS) {
+                this.#cnt[start]--;
+                this.#cnt[end]++;
+
+                if (!this.#cnt[start]) delete this.#cnt[start];
+                if (!this.#cnt[end]) delete this.#cnt[end];
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->
diff --git a/solution/0700-0799/0731.My Calendar II/Solution3.js b/solution/0700-0799/0731.My Calendar II/Solution3.js
new file mode 100644
index 0000000000000..86fcb55a25ca9
--- /dev/null
+++ b/solution/0700-0799/0731.My Calendar II/Solution3.js	
@@ -0,0 +1,25 @@
+class MyCalendarTwo {
+    #OVERLAPS = 2;
+    #cnt = {};
+
+    book(start, end) {
+        this.#cnt[start] = (this.#cnt[start] ?? 0) + 1;
+        this.#cnt[end] = (this.#cnt[end] ?? 0) - 1;
+
+        let sum = 0;
+        for (const v of Object.values(this.#cnt)) {
+            sum += v;
+            if (sum > this.#OVERLAPS) {
+                this.#cnt[start]--;
+                this.#cnt[end]++;
+
+                if (!this.#cnt[start]) delete this.#cnt[start];
+                if (!this.#cnt[end]) delete this.#cnt[end];
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
diff --git a/solution/0700-0799/0731.My Calendar II/Solution3.ts b/solution/0700-0799/0731.My Calendar II/Solution3.ts
new file mode 100644
index 0000000000000..29d9836756197
--- /dev/null
+++ b/solution/0700-0799/0731.My Calendar II/Solution3.ts	
@@ -0,0 +1,25 @@
+class MyCalendarTwo {
+    #OVERLAPS = 2;
+    #cnt: Record<number, number> = {};
+
+    book(start: number, end: number): boolean {
+        this.#cnt[start] = (this.#cnt[start] ?? 0) + 1;
+        this.#cnt[end] = (this.#cnt[end] ?? 0) - 1;
+
+        let sum = 0;
+        for (const v of Object.values(this.#cnt)) {
+            sum += v;
+            if (sum > this.#OVERLAPS) {
+                this.#cnt[start]--;
+                this.#cnt[end]++;
+
+                if (!this.#cnt[start]) delete this.#cnt[start];
+                if (!this.#cnt[end]) delete this.#cnt[end];
+
+                return false;
+            }
+        }
+
+        return true;
+    }
+}