feat(remove-linked-list-elements): 递归 | 迭代

Author: oushihao

assets/data/category.json

@@ -271,6 +271,12 @@
         "path": "../../problemset/sort-list/README.md",
         "difficulty": "中等"
       },
+      {
+        "id": 203,
+        "title": "移除链表元素",
+        "path": "../../problemset/remove-linked-list-elements/README.md",
+        "difficulty": "简单"
+      },
       {
         "id": 432,
         "title": "全 O(1) 的数据结构",
@@ -1628,6 +1634,12 @@
         "path": "../../problemset/number-of-islands/README.md",
         "difficulty": "中等"
       },
+      {
+        "id": 203,
+        "title": "移除链表元素",
+        "path": "../../problemset/remove-linked-list-elements/README.md",
+        "difficulty": "简单"
+      },
       {
         "id": 589,
         "title": "N 叉树的前序遍历",

assets/data/problems.json

@@ -1779,6 +1779,16 @@
     "url": "https://leetcode-cn.com/problems/happy-number/",
     "path": "../../problemset/happy-number/README.md"
   },
+  {
+    "id": 203,
+    "title": {
+      "cn": "移除链表元素",
+      "en": "remove-linked-list-elements"
+    },
+    "difficulty": "简单",
+    "url": "https://leetcode-cn.com/problems/remove-linked-list-elements/",
+    "path": "../../problemset/remove-linked-list-elements/README.md"
+  },
   {
     "id": 258,
     "title": {

assets/docs/CATEGORY.md

@@ -53,6 +53,7 @@
 | 146. [LRU缓存](../../problemset/lru-cache/README.md) | 中等 |
 | 147. [对链表进行插入排序](../../problemset/insertion-sort-list/README.md) | 中等 |
 | 148. [排序链表](../../problemset/sort-list/README.md) | 中等 |
+| 203. [移除链表元素](../../problemset/remove-linked-list-elements/README.md) | 简单 |
 | 432. [全 O(1) 的数据结构](../../problemset/all-oone-data-structure/README.md) | 困难 |
 
 ## 滑动窗口
@@ -325,6 +326,7 @@
 | 173. [二叉搜索树迭代器](../../problemset/binary-search-tree-iterator/README.md) | 中等 |
 | 199. [二叉树的右视图](../../problemset/binary-tree-right-side-view/README.md) | 中等 |
 | 200. [岛屿数量](../../problemset/number-of-islands/README.md) | 中等 |
+| 203. [移除链表元素](../../problemset/remove-linked-list-elements/README.md) | 简单 |
 | 589. [N 叉树的前序遍历](../../problemset/n-ary-tree-preorder-traversal/README.md) | 简单 |
 | 590. [N 叉树的后序遍历](../../problemset/n-ary-tree-postorder-traversal/README.md) | 简单 |
 | 606. [根据二叉树创建字符串](../../problemset/construct-string-from-binary-tree/README.md) | 简单 |

assets/docs/PROBLEMS.md

@@ -356,6 +356,8 @@
 
 [202. 快乐数](../../problemset/happy-number/README.md)
 
+[203. 移除链表元素](../../problemset/remove-linked-list-elements/README.md)
+
 [258. 各位相加](../../problemset/add-digits/README.md)
 
 [300. 最长递增子序列](../../problemset/longest-increasing-subsequence/README.md)

problemset/remove-linked-list-elements/README.md

@@ -0,0 +1,84 @@
+# 移除链表元素
+
+> 难度：简单
+>
+> https://leetcode-cn.com/problems/remove-linked-list-elements/
+
+## 题目
+
+给你一个链表的头节点 `head` 和一个整数 `val` ，请你删除链表中所有满足
+`Node.val == val` 的节点，并返回 **新的头节点** 。
+
+### 示例
+
+#### 示例 1
+
+![remove-linked-list-elements](https://user-images.githubusercontent.com/54696834/159191813-06207770-83fa-4c1b-a7ee-cc765f7f9cfd.jpg)
+
+```
+输入：head = [1,2,6,3,4,5,6], val = 6
+输出：[1,2,3,4,5]
+```
+
+#### 示例 2
+
+```
+输入：head = [], val = 1
+输出：[]
+```
+
+#### 示例 3
+
+```
+输入：head = [7,7,7,7], val = 7
+输出：[]
+```
+
+## 解题
+
+### 递归
+
+```typescript
+/**
+ * 递归
+ * @desc 时间复杂度 O(N)  空间复杂度 O(N)
+ * @param head
+ * @param val
+ * @returns
+ */
+export function removeElements(
+  head: ListNode | null,
+  val: number
+): ListNode | null {
+  if (head === null) return head;
+  head.next = removeElements(head.next, val);
+  return head.val === val ? head.next : head;
+}
+```
+
+### 迭代
+
+```typescript
+/**
+ * 迭代
+ * @desc 时间复杂度 O(N)  空间复杂度 O(1)
+ * @param head
+ * @param val
+ * @returns
+ */
+export function removeElements2(
+  head: ListNode | null,
+  val: number
+): ListNode | null {
+  const dummyHead = new ListNode(0, head);
+  let temp = dummyHead;
+  while (temp.next !== null) {
+    if (temp.next.val == val) {
+      temp.next = temp.next.next;
+    } else {
+      temp = temp.next;
+    }
+  }
+  return dummyHead.next;
+}
+```

problemset/remove-linked-list-elements/index.spec.ts

@@ -0,0 +1,35 @@
+import { ListNode, createListNode } from '~/utils/listNode';
+import { removeElements, removeElements2 } from '.';
+
+describe('移除链表元素', () => {
+  describe('递归', () => {
+    testCase(removeElements);
+  });
+
+  describe('迭代', () => {
+    testCase(removeElements2);
+  });
+});
+
+function testCase(fn: (head: ListNode | null, val: number) => ListNode | null) {
+  it('示例一', () => {
+    const head = createListNode([1, 2, 6, 3, 4, 5, 6]);
+    const val = 6;
+    const expected = createListNode([1, 2, 3, 4, 5]);
+    expect(fn(head, val)).toStrictEqual(expected);
+  });
+
+  it('示例二', () => {
+    const head = createListNode([]);
+    const val = 1;
+    const expected = createListNode([]);
+    expect(fn(head, val)).toStrictEqual(expected);
+  });
+
+  it('示例三', () => {
+    const head = createListNode([7, 7, 7, 7]);
+    const val = 7;
+    const expected = createListNode([]);
+    expect(fn(head, val)).toStrictEqual(expected);
+  });
+}

problemset/remove-linked-list-elements/index.ts

@@ -0,0 +1,40 @@
+import { ListNode } from '~/utils/listNode';
+
+/**
+ * 递归
+ * @desc 时间复杂度 O(N)  空间复杂度 O(N)
+ * @param head
+ * @param val
+ * @returns
+ */
+export function removeElements(
+  head: ListNode | null,
+  val: number
+): ListNode | null {
+  if (head === null) return head;
+  head.next = removeElements(head.next, val);
+  return head.val === val ? head.next : head;
+}
+
+/**
+ * 迭代
+ * @desc 时间复杂度 O(N)  空间复杂度 O(1)
+ * @param head
+ * @param val
+ * @returns
+ */
+export function removeElements2(
+  head: ListNode | null,
+  val: number
+): ListNode | null {
+  const dummyHead = new ListNode(0, head);
+  let temp = dummyHead;
+  while (temp.next !== null) {
+    if (temp.next.val == val) {
+      temp.next = temp.next.next;
+    } else {
+      temp = temp.next;
+    }
+  }
+  return dummyHead.next;
+}