feat: add ts solution to lc problem: No.0141

No.0141.Linked List Cycle

Author: YangFong

solution/0100-0199/0141.Linked List Cycle/README.md

@@ -62,6 +62,12 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+**方法一：哈希表**
+
+遍历链表，并使用哈希表记录每个节点。当某个节点二次出现时，则表示存在环，直接返回 `true`。否则链表遍历结束，返回 `false`。
+
+**方法二：快慢指针**
+
 定义快慢指针 `slow`、`fast`，初始指向 `head`。
 
 快指针每次走两步，慢指针每次走一步，不断循环。当相遇时，说明链表存在环。如果循环结束依然没有相遇，说明链表不存在环。
@@ -200,6 +206,65 @@ func hasCycle(head *ListNode) bool {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function hasCycle(head: ListNode | null): boolean {
+    const set = new Set<ListNode>();
+    let node = head;
+    while (node != null) {
+        if (set.has(node)) {
+            return true;
+        }
+        set.add(node);
+        node = node.next;
+    }
+    return false;
+}
+```
+
+```ts
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function hasCycle(head: ListNode | null): boolean {
+    if (head == null) {
+        return false;
+    }
+    let slow = head;
+    let fast = head.next;
+    while (fast != null && fast.next != null) {
+        if (slow == fast) {
+            return true;
+        }
+        slow = slow.next;
+        fast = fast.next.next;
+    }
+    return false;
+}
+```
+
 ### **...**
 
 ```

solution/0100-0199/0141.Linked List Cycle/README_EN.md

@@ -179,6 +179,65 @@ func hasCycle(head *ListNode) bool {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function hasCycle(head: ListNode | null): boolean {
+    const set = new Set<ListNode>();
+    let node = head;
+    while (node != null) {
+        if (set.has(node)) {
+            return true;
+        }
+        set.add(node);
+        node = node.next;
+    }
+    return false;
+}
+```
+
+```ts
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function hasCycle(head: ListNode | null): boolean {
+    if (head == null) {
+        return false;
+    }
+    let slow = head;
+    let fast = head.next;
+    while (fast != null && fast.next != null) {
+        if (slow == fast) {
+            return true;
+        }
+        slow = slow.next;
+        fast = fast.next.next;
+    }
+    return false;
+}
+```
+
 ### **...**
 
 ```

solution/0100-0199/0141.Linked List Cycle/Solution.ts

@@ -0,0 +1,24 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function hasCycle(head: ListNode | null): boolean {
+    const set = new Set<ListNode>();
+    let node = head;
+    while (node != null) {
+        if (set.has(node)) {
+            return true;
+        }
+        set.add(node);
+        node = node.next;
+    }
+    return false;
+}