diff --git a/problems/0019.删除链表的倒数第N个节点.md b/problems/0019.删除链表的倒数第N个节点.md index e041937f..813e9b02 100644 --- a/problems/0019.删除链表的倒数第N个节点.md +++ b/problems/0019.删除链表的倒数第N个节点.md @@ -181,7 +181,71 @@ var removeNthFromEnd = function(head, n) { return ret.next; }; ``` +TypeScript: + +版本一(快慢指针法): + +```typescript +function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null { + let newHead: ListNode | null = new ListNode(0, head); + let slowNode: ListNode | null = newHead, + fastNode: ListNode | null = newHead; + for (let i = 0; i < n; i++) { + fastNode = fastNode.next; + } + while (fastNode.next) { + fastNode = fastNode.next; + slowNode = slowNode.next; + } + slowNode.next = slowNode.next.next; + return newHead.next; +}; +``` + +版本二(计算节点总数法): + +```typescript +function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null { + let curNode: ListNode | null = head; + let listSize: number = 0; + while (curNode) { + curNode = curNode.next; + listSize++; + } + if (listSize === n) { + head = head.next; + } else { + curNode = head; + for (let i = 0; i < listSize - n - 1; i++) { + curNode = curNode.next; + } + curNode.next = curNode.next.next; + } + return head; +}; +``` + +版本三(递归倒退n法): + +```typescript +function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null { + let newHead: ListNode | null = new ListNode(0, head); + let cnt = 0; + function recur(node) { + if (node === null) return; + recur(node.next); + cnt++; + if (cnt === n + 1) { + node.next = node.next.next; + } + } + recur(newHead); + return newHead.next; +}; +``` + Kotlin: + ```Kotlin fun removeNthFromEnd(head: ListNode?, n: Int): ListNode? { val pre = ListNode(0).apply {