https://leetcode.cn/problems/merge-two-sorted-lists/submissions/558715098/?envType=study-plan-v2&envId=top-100-liked
简单题，链表合并
```js
var mergeTwoLists = function (list1, list2) {
let head = { next: null }
const ret = head
while (list1 != null && list2 != null) {
if (list1.val < list2.val) {
head.next = list1
list1 = list1.next
head = head.next
} else {
head.next = list2
list2 = list2.next
head = head.next
}
}
do {
if (list2) {
head.next = list2
list2 = list2.next
head = head.next
}
if (list1) {
head.next = list1
list1 = list1.next
head = head.next
}
} while (list1 != null || list2 != null);
return ret.next
};
```
王一之 发表于 2024-8-26 16:57
我提议新开一个catcode平台，重新进行排名
这样我就可以给自己改成第一了！
https://leetcode.cn/problems/add-two-numbers/submissions/558720843/?envType=study-plan-v2&envId=top-100-liked
简单题
```js
var addTwoNumbers = function (l1, l2) {
let add = 0
let head = {
next: null
}
let ret = head
while (l1 != null || l2 != null) {
const num1 = l1?.val ?? 0
const num2 = l2?.val ?? 0
let total = num1 + num2 + add
add =0
if(total>=10){
total-=10
add=1
}
head.next = {
val: total,
next: null
}
head = head.next
l1 = l1?.next;
l2 = l2?.next
}
if (add !== 0) {
head.next = {
val: add,
next: null
}
}
return ret.next
};
```
https://leetcode.cn/problems/remove-nth-node-from-end-of-list/submissions/558725242/?envType=study-plan-v2&envId=top-100-liked
边界有点难控制，其他没了
```js
var removeNthFromEnd = function (head, n) {
if(head.next==null&&n==1){
return null
}
let fast = head
let slow = head
for (let index = 0; index < n; index++) {
fast = fast.next
}
if(fast==null){
return head.next
}
while (fast?.next != null) {
slow = slow.next
fast = fast.next
}
slow.next=slow?.next?.next??null
return head
};
```
https://leetcode.cn/problems/swap-nodes-in-pairs/submissions/558728046/?envType=study-plan-v2&envId=top-100-liked
简单交换题
```js
var swapPairs = function (head) {
if(head?.next==null){
return head
}
const ret = {
next:null
}
let setHead=ret
while (head?.next != null) {
let first = head
let last = head.next
head = last.next
first.next = last.next;
last.next = first
setHead.next=last
setHead=first
}
return ret.next
};
```
https://leetcode.cn/problems/number-of-steps-to-reduce-a-number-to-zero/submissions/558730132/
简单题水一下换换心情
```js
var numberOfSteps = function (num) {
let times = 0
while (num != 0) {
num = num % 2 == 0 ? num / 2 : num - 1;
times++
}
return times
};
```
https://leetcode.cn/problems/reverse-nodes-in-k-group/submissions/558836129/?envType=study-plan-v2&envId=top-100-liked
还算可以
边界判断蒙了
```js
var reverseKGroup = function (head, k) {
let fast = head;
let slow = head;
let ret = { next: null };
let chain = ret;
while (slow != null) {
let isJump=false
for (let index = 0; index < k; index++) {
fast = fast.next;
if (fast == null) {
if(index!=k-1){
isJump=true
}
break;
}
}
if (isJump) {
chain.next = slow;
break;
}
let last = null;
let first = slow;
while (slow != fast) {
let next = slow.next;
slow.next = last;
last = slow;
slow = next;
}
chain.next = last;
chain = first;
}
return ret.next;
};
```
https://leetcode.cn/problems/copy-list-with-random-pointer/submissions/560906494/?envType=study-plan-v2&envId=top-100-liked
凹了一晚上才凹出来
思路歪了...
```js
var copyRandomList = function (head) {
if(head==null){
return null
}
let chainPoint = head
do {
const val = chainPoint.val
const next = chainPoint.next
const newNode = {
val,
next
}
chainPoint.next = newNode
chainPoint = chainPoint?.next?.next
} while (chainPoint != null);
let coptPoint = head
while (coptPoint != null) {
coptPoint.next.random = coptPoint?.random?.next ?? null
coptPoint = coptPoint?.next?.next
}
let newChain = {
next: null
}
const ret = newChain
while (head != null) {
newChain.next = head.next;
newChain = newChain.next
head.next = head?.next?.next ?? null
head = head.next
}
return ret.next
};
```
https://leetcode.cn/problems/sort-list/?envType=study-plan-v2&envId=top-100-liked
打一波归序，但是快慢指针控制的不好
边界过多了
```js
var sortList = function (head, end = undefined) {
if (head?.next == end) {
return head
}
let slow = head?.next;//第二段开头
let first = head;//第一段结尾
let fast = head?.next;//第二个结尾
if (fast != end) {
fast = fast?.next
if (fast?.next != end) {
while (fast != end) {
slow = slow?.next;
fast = fast?.next?.next;
if (fast?.next == end) {
fast = fast?.next
break;
}
}
}else{
fast = fast?.next
}
}
let china1 = sortList(first, slow)
let china2 = sortList(slow, end)
let headptr = {
next: null
}
const ptr = headptr
while (china1 != slow || china2 != fast) {
if (china1 != slow && china2 != fast) {
const num1 = china1?.val;
const num2 = china2?.val;
if (num1 < num2) {
headptr.next = china1
china1 = china1.next;
} else {
headptr.next = china2
china2 = china2.next;
}
} else {
headptr.next = china1 != slow ? china1 : china2
if (china1 != slow) {
china1 = china1.next;
} else {
china2 = china2.next;
}
}
headptr = headptr.next
}
headptr.next = end ?? null
return ptr.next
};
```
https://leetcode.cn/problems/middle-of-the-linked-list/submissions/560909018/
简单题直接秒
```js
var middleNode = function (head) {
let slow = head
let fast = head
while (fast != null&&fast.next!=null) {
fast = fast?.next;
slow = slow.next
fast = fast?.next;
}
return slow
};
```