Merge pull request #619 from YDLIN/master

添加0707.设计链表 Swift版本
This commit is contained in:
程序员Carl
2021-08-20 08:19:47 +08:00
committed by GitHub

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@ -948,72 +948,91 @@ class MyLinkedList {
} }
``` ```
Swift
```Swift
class MyLinkedList {
var size = 0
let head: ListNode
/** Initialize your data structure here. */ Swift:
```swift
class MyLinkedList {
var dummyHead: ListNode<Int>?
var size: Int
init() { init() {
head = ListNode(-1) dummyHead = ListNode(0)
size = 0
} }
/** Get the value of the index-th node in the linked list. If the index is invalid, return -1. */
func get(_ index: Int) -> Int { func get(_ index: Int) -> Int {
if size > 0 && index < size { if index >= size || index < 0 {
var tempHead = head
for _ in 0..<index {
tempHead = tempHead.next!
}
let currentNode = tempHead.next!
return currentNode.val
} else {
return -1 return -1
} }
var curNode = dummyHead?.next
var curIndex = index
while curIndex > 0 {
curNode = curNode?.next
curIndex -= 1
}
return curNode?.value ?? -1
} }
/** Add a node of value val before the first element of the linked list. After the insertion, the new node will be the first node of the linked list. */
func addAtHead(_ val: Int) { func addAtHead(_ val: Int) {
addAtIndex(0, val) let newHead = ListNode(val)
newHead.next = dummyHead?.next
dummyHead?.next = newHead
size += 1
} }
/** Append a node of value val to the last element of the linked list. */
func addAtTail(_ val: Int) { func addAtTail(_ val: Int) {
addAtIndex(size, val) let newNode = ListNode(val)
var curNode = dummyHead
while curNode?.next != nil {
curNode = curNode?.next
}
curNode?.next = newNode
size += 1
} }
/** Add a node of value val before the index-th node in the linked list. If index equals to the length of linked list, the node will be appended to the end of linked list. If index is greater than the length, the node will not be inserted. */
func addAtIndex(_ index: Int, _ val: Int) { func addAtIndex(_ index: Int, _ val: Int) {
if index > size { if index > size {
return return
} }
let idx = (index >= 0 ? index : 0)
var tempHead = head let newNode = ListNode(val)
for _ in 0 ..< idx { var curNode = dummyHead
tempHead = tempHead.next! var curIndex = index
while curIndex > 0 {
curNode = curNode?.next
curIndex -= 1
} }
let currentNode = tempHead.next
let newNode = ListNode(val, currentNode) newNode.next = curNode?.next
tempHead.next = newNode curNode?.next = newNode
size += 1 size += 1
} }
/** Delete the index-th node in the linked list, if the index is valid. */
func deleteAtIndex(_ index: Int) { func deleteAtIndex(_ index: Int) {
if size > 0 && index < size { if index >= size || index < 0 {
var tempHead = head return
for _ in 0 ..< index {
tempHead = tempHead.next!
}
tempHead.next = tempHead.next!.next
size -= 1
} }
var curNode = dummyHead
for _ in 0..<index {
curNode = curNode?.next
}
curNode?.next = curNode?.next?.next
size -= 1
} }
} }
``` ```
----------------------- -----------------------
* 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw) * 作者微信:[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
* B站视频[代码随想录](https://space.bilibili.com/525438321) * B站视频[代码随想录](https://space.bilibili.com/525438321)