LeetCode 链表-编程实验室

LeetCode 链表简单题 + 可直接本地运行的 JS 版本，每道题都包含：

链表节点构造函数
数组转链表 / 链表转数组（方便本地调试）
完整可运行代码
测试用例

你直接复制到浏览器控制台 / Node.js 就能跑，不用改任何东西！

先写通用工具函数（所有题都能用）

// 1. 链表节点构造函数 function ListNode(val, next) { this.val = val === undefined ? 0 : val; this.next = next === undefined ? null : next; } // 2. 数组 => 链表 function arrayToList(arr) { let dummy = new ListNode(); let cur = dummy; for (let num of arr) { cur.next = new ListNode(num); cur = cur.next; } return dummy.next; } // 3. 链表 => 数组（方便打印看结果） function listToArray(head) { let res = []; while (head) { res.push(head.val); head = head.next; } return res; }

下面所有题直接复制就能调试～

1. 反转链表 206

function reverseList(head) { let prev = null; let cur = head; while (cur) { let next = cur.next; cur.next = prev; prev = cur; cur = next; } return prev; } // 测试 let head = arrayToList([1,2,3,4,5]); console.log(listToArray(reverseList(head))); // [5,4,3,2,1]

2. 合并两个有序链表 21

function mergeTwoLists(l1, l2) { let dummy = new ListNode(); let cur = dummy; while (l1 && l2) { if (l1.val < l2.val) { cur.next = l1; l1 = l1.next; } else { cur.next = l2; l2 = l2.next; } cur = cur.next; } cur.next = l1 || l2; return dummy.next; } // 测试 let l1 = arrayToList([1,2,4]); let l2 = arrayToList([1,3,4]); console.log(listToArray(mergeTwoLists(l1, l2))); // [1,1,2,3,4,4]

3. 删除排序链表中的重复元素 83

function deleteDuplicates(head) { let cur = head; while (cur && cur.next) { if (cur.val === cur.next.val) { cur.next = cur.next.next; } else { cur = cur.next; } } return head; } // 测试 let head = arrayToList([1,1,2,3,3]); console.log(listToArray(deleteDuplicates(head))); // [1,2,3]

4. 环形链表 141

function hasCycle(head) { let slow = head, fast = head; while (fast && fast.next) { slow = slow.next; fast = fast.next.next; if (slow === fast) return true; } return false; } // 测试 let head = arrayToList([3,2,0,-4]); head.next.next.next = head; // 造环 console.log(hasCycle(head)); // true

5. 链表的中间节点 876

function middleNode(head) { let slow = head, fast = head; while (fast && fast.next) { slow = slow.next; fast = fast.next.next; } return slow; } // 测试 let head = arrayToList([1,2,3,4,5]); console.log(listToArray(middleNode(head))); // [3,4,5]

6. 删除链表的倒数第 N 个节点 19

function removeNthFromEnd(head, n) { let dummy = new ListNode(0, head); let fast = dummy, slow = dummy; for (let i = 0; i <= n; i++) fast = fast.next; while (fast) { fast = fast.next; slow = slow.next; } slow.next = slow.next.next; return dummy.next; } // 测试 let head = arrayToList([1,2,3,4,5]); console.log(listToArray(removeNthFromEnd(head, 2))); // [1,2,3,5]

7. 回文链表 234

function isPalindrome(head) { let slow = head, fast = head; let prev = null; while (fast && fast.next) { fast = fast.next.next; let next = slow.next; slow.next = prev; prev = slow; slow = next; } while (prev) { if (prev.val !== slow.val) return false; prev = prev.next; slow = slow.next; } return true; } // 测试 let head = arrayToList([1,2,2,1]); console.log(isPalindrome(head)); // true

8. 相交链表 160

function getIntersectionNode(headA, headB) { let a = headA, b = headB; while (a !== b) { a = a ? a.next : headB; b = b ? b.next : headA; } return a; } // 测试逻辑略，本地可直接跑 LeetCode 用例

9. 移除链表元素 203

function removeElements(head, val) { let dummy = new ListNode(0, head); let cur = dummy; while (cur.next) { if (cur.next.val === val) { cur.next = cur.next.next; } else { cur = cur.next; } } return dummy.next; } // 测试 let head = arrayToList([1,2,6,3,4,5,6]); console.log(listToArray(removeElements(head, 6))); // [1,2,3,4,5]