https://leetcode.cn/problems/summary-ranges/submissions/573763991/?envType=study-plan-v2&envId=top-interview-150
简单题，收工
```js
var summaryRanges = function (nums) {
if (nums.length == 1) {
return ["" + nums]
}
const result = []
nums.push("")
let startNum = nums;
let endNum = nums
for (let index = 1; index < nums.length; index++) {
const num = nums;
if (num == endNum + 1) {
endNum = endNum + 1
} else {
result.push(startNum == endNum ? "" + endNum : startNum + "->" + endNum)
startNum = nums
endNum = nums
}
}
return result
};
```
https://leetcode.cn/problems/permutation-in-string/submissions/573963026/
复杂hash表问题
主要就是考coding能力...
```js
var checkInclusion = function (s1, s2) {
const hash = new Map();
for (let index = 0; index < s1.length; index++) {
const char = s1;
hash.set(char, (hash.get(char) ?? 0) + 1)
}
let max = hash.size;
for (let index = 0; index < s1.length; index++) {
const char = s2;
if (hash.has(char)) {
const nums = hash.get(char)
if (nums == 1) {
max--;
}
hash.set(char, nums - 1)
}
}
if (max == 0) {
return true;
}
for (let index = s1.length; index < s2.length; index++) {
if (index == 8) {
debugger
}
const char = s2;
if (hash.has(char)) {
const nums = hash.get(char)
if (nums == 1) {
max--;
}
hash.set(char, nums - 1)
}
const popNum = hash.get(s2)
if (popNum !== undefined) {
if (popNum == 0) {
max++;
}
hash.set(s2, popNum + 1)
}
if (max == 0) {
return true;
}
}
return false
};
```
https://leetcode.cn/problems/minimum-operations-to-make-binary-array-elements-equal-to-one-ii/submissions/573963836/
一次过，露头就秒！
```js
var minOperations = function (nums) {
let times = 0;
let isReserver = false
for (let index = 0; index < nums.length; index++) {
let num = nums
if (isReserver) {
num = num == 1 ? 0 : 1
}
if (num == 0) {
times++;
isReserver = !isReserver
}
}
return times
};
```
https://leetcode.cn/problems/count-the-number-of-inversions/submissions/573976840/?envType=daily-question&envId=2024-10-17
这题前几天没做出来
终于搞懂了
太复杂了...
```js
var numberOfPermutations = function (n, requirements) {
const req = new Map()
for (const item of requirements) {
req.set(item, item)
}
if (req !== 0 && req !== undefined) {
return 0
}
const cache = new Array(n).fill(0).map(() => new Array(req.get(n - 1)+1).fill(-1))
const dfs = (pos, needNums) => {
if (pos == 0) {
return needNums == 0 ? 1 : 0
}
if (cache !== -1) {
return cache
}
const nextNeed = req.get(pos - 1)
if (nextNeed == undefined) {
const minIndex = Math.min(pos, needNums);
let num = 0;
for (let index = 0; index <= minIndex; index++) {
num += dfs(pos - 1, needNums - index)
num = num % 1000000007
}
cache = num
return num
//不存在
} else {
if (needNums < nextNeed) {
cache = 0
return 0
}
if (needNums - pos > nextNeed) {
cache = 0
return 0
}
const result = dfs(pos - 1, nextNeed) % 1000000007
cache = result
return result
}
}
return dfs(n - 1, req.get(n - 1))
};
```
https://leetcode.cn/problems/average-of-levels-in-binary-tree/submissions/573981968/?envType=study-plan-v2&envId=top-interview-150
二叉树遍历
秒了
```js
var averageOfLevels = function (root) {
const stack = []
const result = []
stack.push(root)
while (stack.length !== 0) {
let val = 0;
let len = stack.length;
for (let index = 0; index < len; index++) {
const item = stack.shift()
val += item.val;
if (item.left != null) {
stack.push(item.left)
}
if (item.right != null) {
stack.push(item.right)
}
}
result.push(val / len)
}
return result
};
```
https://leetcode.cn/problems/smallest-range-i/submissions/574158049/
一开始以为贼复杂...
直到下决心试试先干一下看看...
发现一次过
```js
var smallestRangeI = function (nums, k) {
const min = Math.min(...nums);
const max = Math.max(...nums);
return (max - min - (2 * k)) < 0 ? 0 : (max - min - (2 * k))
};
```
https://leetcode.cn/problems/reverse-integer/submissions/574321327/
简单题，今天累了水一下
```js
var reverse = function (x) {
let result = 0;
const isNeg = x < 0 ? -1 : 1;
x=Math.abs(x)
while (x !== 0) {
result = result * 10
result += x % 10;
x = Math.floor(x / 10)
}
if (result<-2147483648||result>2147483647){
return 0
}
return result * isNeg
};
```
https://leetcode.cn/problems/rotate-list/submissions/574326188/
链表题
凑个数睡觉
```js
var rotateRight = function (head, k) {
if(head==null){
return head
}
let len = 1;
let originHead = head
while (head.next != null) {
head = head.next;
len++;
}
k = k % len
if (k == 0) {
return originHead
}
len = len - k ;
head.next = originHead;
for (let index = 0; index < len; index++) {
head = head.next;
}
let ret = head.next;
head.next = null;
return ret
};
```
https://leetcode.cn/problems/recover-binary-search-tree/submissions/574555795/
基础题，直接秒了
```js
var recoverTree = function (root) {
let firstNode = null;
let secondNode = null;
let lastNode = null;
const dfs = (node) => {
if (node == null) {
return;
}
dfs(node.left)
if (lastNode !== null) {
if (lastNode.val > node.val) {
firstNode = firstNode ?? lastNode
secondNode = node
}
}
lastNode = node;
dfs(node.right)
}
dfs(root)
const firstVal = firstNode.val;
firstNode.val = secondNode.val;
secondNode.val = firstVal
};
```
https://leetcode.cn/problems/first-missing-positive/submissions/574564523/
秒了
```js
var firstMissingPositive = function (nums) {
let l = 0;
let r = nums.length;
const swap = (a, b) => {
const temp = nums;
nums = nums
nums = temp
}
for (let index = 0; index < nums.length; index++) {
while (nums > 0 && nums <= nums.length && nums - 1] !== nums) {
swap(index, nums - 1)
}
}
for (let index = 0; index < nums.length; index++) {
const num = nums;
if (num !== index + 1) {
return index + 1
}
}
return nums.length + 1
};
```