https://leetcode.cn/problems/reverse-linked-list/
反转链表
```js
var reverseList = function(head) {
let pre=null;
while(head!=null){
const next=head.next;
head.next=pre;
pre=head;
head=next;
}
return pre
};
```
https://leetcode.cn/problems/reorder-list/submissions/591128737/
没太理解
但是过了...
```js
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} head
* @Return {ListNode}
*/
var reverseList = function (head) {
let pre = null;
while (head != null) {
const next = head.next;
head.next = pre;
pre = head;
head = next;
}
return pre;
};
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} head
* @return {ListNode}
*/
var middleNode = function (head) {
let slow = head;
let fast = head;
while (fast?.next != null) {
fast = fast.next?.next;
slow = slow.next;
}
return slow;
};
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} head
* @return {void} Do not return anything, modify head in-place instead.
*/
var reorderList = function (head) {
let mid = middleNode(head);
let head2 = reverseList(mid);
let ans=head
while(head2.next!==null){
const next=head.next;
const next2=head2.next;
head.next=head2;
head2.next=next;
head=next;
head2=next2
}
return ans
};
```
https://leetcode.cn/problems/binary-tree-preorder-traversal/submissions/591129441/
秒了
```js
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @Return {number[]}
*/
var preorderTraversal = function(root) {
const result = []; function traverse(node) { if (!node) return; result.push(node.val); traverse(node.left); traverse(node.right); } traverse(root); return result;
};
```
https://leetcode.cn/problems/binary-tree-postorder-traversal/submissions/591129599/
后续
```js
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @Return {number[]}
*/
var postorderTraversal = function(root) {
const result = [];
function traverse(node) {
if (!node) return;
traverse(node.left);
traverse(node.right);
result.push(node.val);
}
traverse(root);
return result;
};
```
https://leetcode.cn/problems/find-minimum-in-rotated-sorted-array-ii/submissions/591135898/
都不知道怎么扣过去的
```js
var findMin = function (nums) {
let l = 0,
r = nums.length - 1;
let min = nums;
while (l <= r) {
const center = l + Math.floor((r - l) / 2);
min = Math.min(min, nums);
if (nums == nums && nums == nums) {
l++;
r--;
continue;
}
if (nums <= nums) {
min = Math.min(min, nums);
l = center + 1;
} else {
min = Math.min(min, nums);
r = center - 1;
}
}
return min;
};
```
https://leetcode.cn/problems/design-an-atm-machine/submissions/591153212/
模拟题，秒了
```js
var ATM = function () {
this.money = new Array(5).fill(0);
};
/**
* @param {number[]} banknotesCount
* @Return {void}
*/
ATM.prototype.deposit = function (banknotesCount) {
for (let index = 0; index < banknotesCount.length; index++) {
const money = banknotesCount;
this.money += money;
}
};
/**
* @param {number} amount
* @return {number[]}
*/
ATM.prototype.withdraw = function (amount) {
const ans = new Array(5).fill(0);
const list = ;
for (let index = 4; index >= 0; index--) {
ans = Math.floor(amount / list);
ans=Math.min(ans,this.money)
amount -= ans * list;
}
if (amount !== 0) {
return [-1];
}
for (let index = 0; index < ans.length; index++) {
const pices = ans;
this.money -= pices;
}
return ans;
};
```
https://leetcode.cn/problems/insertion-sort-list/submissions/591160212/
插入排序
秒了
```js
var insertionSortList = function (head) {
let ans = null;
let node = head;
const insert = (node) => {
let list = ans;
if (list == null) {
node.next = null;
ans = node;
return;
}
if (node.val <= list.val) {
node.next = list;
ans = node;
return;
}
pre = list;
while (list.next !== null) {
if (node.val <= list.val) {
pre.next = node;
node.next = list;
return;
}
pre = list;
list = list.next;
}
if (node.val <= list.val) {
pre.next = node;
node.next = list;
} else {
node.next = null;
list.next = node;
}
};
while (node !== null) {
let next = node.next;
insert(node);
node = next;
}
return ans;
};
```
https://leetcode.cn/problems/count-primes/submissions/591166551/
靠缓存硬打过去了
```js
function isPrime(num) {
if (num <= 3) {
return num > 1;
} else {
let sq = Math.sqrt(num);
for (let i = 2; i <= sq; i++) {
if (num % i === 0) {
return 0;
}
}
return 1;
}
}
/**
* @param {number} n
* @Return {number}
*/
const cache = new Map();
var countPrimes = function (n) {
let ans =0 ;
for (let index = n - 1; index >= 1; index--) {
if (cache.has(index)) {
ans += cache.get(index);
break;
}
ans += isPrime(index);
}
cache.set(n-1,ans)
return ans;
};
```
https://leetcode.cn/problems/maximum-consecutive-floors-without-special-floors/submissions/591336871/
这个题是真的简单
```js
var maxConsecutive = function (bottom, top, special) {
special.sort((a, b) => a - b);
let max = 0;
for (let index = 1; index < special.length; index++) {
max = Math.max(max, special - special - 1);
}
max=Math.max(max,special-bottom,top-special)
return max
};
```
https://leetcode.cn/problems/house-robber-ii/submissions/591340469/
打家劫舍
```js
var rob1 = function (nums, l, r) {
const map = new Map();
const robHouse = (l) => {
if (l > r) {
return 0;
}
if (map.has(l)) {
return map.get(l);
}
const result1 = nums + robHouse(l + 2);
const result2 = robHouse(l + 1);
const result = Math.max(result1, result2);
map.set(l, result);
return result;
};
return robHouse(l);
};
/**
* @param {number[]} nums
* @Return {number}
*/
var rob = function (nums) {
return Math.max(nums + rob1(nums, 2, nums.length - 2),rob1(nums, 1, nums.length - 1));
};
```