Merge pull request #2323 from xin0907/master

update: 0053.最大子序和修复 ts 解法 BUG & 1035.不相交线 ts 新增滚动数组解法 & 优化 1035.不相交的线 ts 滚动数组代码注释 & 优化 0392.判断子序列 ts 二维数组解法代码逻辑 & 0392.判断子序列 ts 新增滚动数组解法。
This commit is contained in:
程序员Carl
2023-11-06 09:48:32 +08:00
committed by GitHub
3 changed files with 79 additions and 22 deletions

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@ -226,18 +226,20 @@ object Solution {
```typescript
function maxSubArray(nums: number[]): number {
/**
dp[i]以nums[i]结尾的最大和
*/
const dp: number[] = []
dp[0] = nums[0];
let resMax: number = 0;
for (let i = 1; i < nums.length; i++) {
dp[i] = Math.max(dp[i - 1] + nums[i], nums[i]);
resMax = Math.max(resMax, dp[i]);
const len = nums.length
if (len === 1) return nums[0]
const dp: number[] = new Array(len)
let resMax: number = dp[0] = nums[0]
for (let i = 1; i < len; i++) {
dp[i] = Math.max(dp[i - 1] + nums[i], nums[i])
// 注意值为负数的情况
if (dp[i] > resMax) resMax = dp[i]
}
return resMax;
};
return resMax
}
```

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@ -216,26 +216,51 @@ const isSubsequence = (s, t) => {
### TypeScript
> 二维数组
```typescript
function isSubsequence(s: string, t: string): boolean {
/**
dp[i][j]: s的前i-1个t的前j-1个最长公共子序列的长度
*/
const sLen: number = s.length,
tLen: number = t.length;
const dp: number[][] = new Array(sLen + 1).fill(0)
.map(_ => new Array(tLen + 1).fill(0));
const sLen = s.length
const tLen = t.length
const dp: number[][] = new Array(sLen + 1).fill(0).map(_ => new Array(tLen + 1).fill(0))
for (let i = 1; i <= sLen; i++) {
for (let j = 1; j <= tLen; j++) {
if (s[i - 1] === t[j - 1]) {
dp[i][j] = dp[i - 1][j - 1] + 1;
} else {
dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
}
if (s[i - 1] === t[j - 1]) dp[i][j] = dp[i - 1][j - 1] + 1
// 只需要取 j-2 的 dp 值即可,不用考虑 i-2
else dp[i][j] = dp[i][j - 1]
}
}
return dp[sLen][tLen] === s.length;
};
return dp[sLen][tLen] === s.length
}
```
> 滚动数组
```typescript
function isSubsequence(s: string, t: string): boolean {
const sLen = s.length
const tLen = t.length
const dp: number[] = new Array(tLen + 1).fill(0)
for (let i = 1; i <= sLen; i++) {
let prev: number = 0;
let temp: number = 0;
for (let j = 1; j <= tLen; j++) {
// 备份一下当前状态(经过上层迭代后的)
temp = dp[j]
// prev 相当于 dp[j-1](累加了上层的状态)
// 如果单纯 dp[j-1] 则不会包含上层状态
if (s[i - 1] === t[j - 1]) dp[j] = prev + 1
else dp[j] = dp[j - 1]
// 继续使用上一层状态更新参数用于当前层下一个状态
prev = temp
}
}
return dp[tLen] === sLen
}
```
### Go

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@ -221,6 +221,8 @@ const maxUncrossedLines = (nums1, nums2) => {
### TypeScript
> 二维数组
```typescript
function maxUncrossedLines(nums1: number[], nums2: number[]): number {
/**
@ -243,6 +245,34 @@ function maxUncrossedLines(nums1: number[], nums2: number[]): number {
};
```
> 滚动数组
```typescript
function maxUncrossedLines(nums1: number[], nums2: number[]): number {
const len1 = nums1.length
const len2 = nums2.length
const dp: number[] = new Array(len2 + 1).fill(0)
for (let i = 1; i <= len1; i++) {
let prev: number = 0;
let temp: number = 0;
for (let j = 1; j <= len2; j++) {
// 备份一下当前状态(经过上层迭代后的)
temp = dp[j]
// prev 相当于 dp[j-1](累加了上层的状态)
// 如果单纯 dp[j-1] 则不会包含上层状态
if (nums1[i - 1] === nums2[j - 1]) dp[j] = prev + 1
// dp[j] 表示之前的 dp[i][j-1]dp[j-1] 表示 dp[i-1][j]
else dp[j] = Math.max(dp[j], dp[j - 1])
// 继续使用上一层状态更新参数用于当前层下一个状态
prev = temp
}
}
return dp[len2]
}
```
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