https://leetcode.cn/problems/to-lower-case/submissions/568756876/?envType=study-plan-v2&envId=primers-list
这个更6
```go
func toLowerCase(s string) string {
return strings.ToLower(s)
}
```
https://leetcode.cn/problems/decode-ways/submissions/568871759/?envType=study-plan-v2&envId=dynamic-programming
爬楼梯的魔改题，dp边界一开始抠蒙了
```js
var numDecodings = function (s) {
const dp = new Array(s.length).fill(0);
if (s !== '0') {
dp = 1;
}
const isValid = (str) => {
if (str == '0') {
return false
}
if (str == '1') {
return true
}
if (str == '2') {
if (parseInt(str) <= 6) {
return true
} else {
return false
}
}
}
for (let index = s.length - 2; index >= 0; index--) {
const char = s;
if (char == '0') {
continue;
}
if (isValid(char + s)) {
dp = dp + (index + 2>=s.length?1:dp)
} else {
dp = dp
}
}
return dp
};
```
https://leetcode.cn/problems/minimum-cost-for-tickets/submissions/568892337/?envType=study-plan-v2&envId=dynamic-programming
缓存秒了！
但是感觉转dp自己维度太多了...
```js
var mincostTickets = function (days, costs) {
days.unshift(days);
const cache = new Map();
const dfs = (pos, day) => {
const flag = `${pos} ${day}`;
if (cache.has(flag)) {
return cache.get(flag);
}
if (pos >= days.length) {
return 0;
}
const lastDay = days - days;
let result = 0;
if (day <= lastDay) {
result = Math.min(
dfs(pos + 1, 1) + costs,
dfs(pos + 1, 7) + costs,
dfs(pos + 1, 30) + costs
);
} else {
result = dfs(pos + 1, day - lastDay);
}
cache.set(flag, result);
return result;
};
return dfs(1, 0);
};
```
https://leetcode.cn/problems/domino-and-tromino-tiling/submissions/569120236/?envType=study-plan-v2&envId=dynamic-programming
这题没凹出来
状态被我设计的太复杂了
```js
var numTilings = function (n) {
const dp = new Array(n).fill(0).map(() => new Array(4).fill(0))
// 0不填充
// 1填充满
// 2上界
// 3下界
dp = 1;
dp = 1;
for (let index = 1; index < dp.length; index++) {
dp = dp
dp = dp + dp + dp + dp
dp = dp + dp
dp = dp + dp
dp= dp%(1000000000 + 7)
dp= dp%(1000000000 + 7)
dp= dp%(1000000000 + 7)
dp= dp%(1000000000 + 7)
}
return dp
};
```
https://leetcode.cn/problems/add-digits/submissions/569132366/?envType=study-plan-v2&envId=primers-list
简单题压压惊
```js
func addDigits(num int) int {
var calc = func(num int) int {
var newNum int
for {
if num == 0 {
break
}
newNum += num % 10
num = num / 10
}
return newNum
}
for {
if num < 10 {
return num
}
num = calc(num)
}
}
```
https://leetcode.cn/problems/subtract-the-product-and-sum-of-digits-of-an-integer/submissions/569134967/?envType=study-plan-v2&envId=primers-list
再练一题go
```js
func subtractProductAndSum(n int) int {
var calc1 = func(num int) int {
var newNum int
for {
if num == 0 {
break
}
newNum += (num % 10)
num = num / 10
}
return newNum
}
var calc2 = func(num int) int {
var newNum int = 1
for {
if num == 0 {
break
}
newNum *= (num % 10)
num = num / 10
}
return newNum
}
return calc2(n) - calc1(n)
}
```
https://leetcode.cn/problems/same-tree/submissions/569139967/?envType=study-plan-v2&envId=top-interview-150
dfs简单题
秒了！
```js
var isSameTree = function (p, q) {
const dfs = (a, b) => {
if (a == null || b == null) {
return a == b
}
if (a.val == b.val) {
const left = dfs(a.left, b.left)
const right = dfs(a.right, b.right)
return left == true && left == right
}
return false
}
return dfs(p, q)
};
```
https://leetcode.cn/problems/maximum-number-of-vowels-in-a-substring-of-given-length/submissions/569146960/
双指针，但是条件判断写的有点脏了
```js
var maxVowels = function (s, k) {
let left = 0;
let right = 0;
let maxNum = "aeiou".indexOf(s) !== -1 ? 1 : 0;
let result = 0
for (let index = 1; index < s.length; index++) {
const char = s;
if ("aeiou".indexOf(char) !== -1) {
//是
if ((right - left + 1) !== k) {
right++;
maxNum++;
} else {
if ("aeiou".indexOf(s) !== -1) {
right++;
left++;
} else {
right++;
left++;
maxNum++;
}
}
} else {
//不是
if ((right - left + 1) !== k) {
right++;
} else {
if ("aeiou".indexOf(s) !== -1) {
result = Math.max(result, maxNum)
right++;
left++;
maxNum--;
} else {
right++;
left++;
}
}
}
}
returnMath.max(result, maxNum)
};
```
https://leetcode.cn/problems/maximum-average-subarray-i/submissions/569147459/
定长顺了，秒！
```js
var findMaxAverage = function (nums, k) {
let pos = 0;
let result = Number.MIN_SAFE_INTEGER;
let avergeNum = 0
for (let index = 0; index < nums.length; index++) {
const num = nums;
avergeNum += num;
pos++;
if (pos <= k-1) {
continue;
}
result = Math.max(result, avergeNum / k)
avergeNum -= nums
}
return result
};
```
https://leetcode.cn/problems/number-of-sub-arrays-of-size-k-and-average-greater-than-or-equal-to-threshold/submissions/569147579/
过
```js
var numOfSubarrays = function (arr, k, threshold) {
let pos = 0;
let result = 0;
let avergeNum = 0;
for (let index = 0; index < arr.length; index++) {
const num = arr;
avergeNum += num;
pos++;
if (pos <= k - 1) {
continue;
}
if((avergeNum / k)>=threshold){
result++
}
avergeNum -= arr
}
return result
};
```