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107
problems/0028.实现strStr.md
View File

@ -1059,5 +1059,112 @@ func getNext(_ next: inout [Int], needle: [Character]) {
```
> 前缀表右移
```swift
func strStr(_ haystack: String, _ needle: String) -> Int {
let s = Array(haystack), p = Array(needle)
guard p.count != 0 else { return 0 }
var j = 0
var next = [Int].init(repeating: 0, count: p.count)
getNext(&next, p)
for i in 0 ..< s.count {
while j > 0 && s[i] != p[j] {
j = next[j]
}
if s[i] == p[j] {
j += 1
}
if j == p.count {
return i - p.count + 1
}
}
return -1
}
// 前缀表后移一位，首位用 -1 填充
func getNext(_ next: inout [Int], _ needle: [Character]) {
guard needle.count > 1 else { return }
var j = 0
next[0] = j
for i in 1 ..< needle.count-1 {
while j > 0 && needle[i] != needle[j] {
j = next[j-1]
}
if needle[i] == needle[j] {
j += 1
}
next[i] = j
}
next.removeLast()
next.insert(-1, at: 0)
}
```
> 前缀表统一不减一
```swift
func strStr(_ haystack: String, _ needle: String) -> Int {
let s = Array(haystack), p = Array(needle)
guard p.count != 0 else { return 0 }
var j = 0
var next = [Int](repeating: 0, count: needle.count)
// KMP
getNext(&next, needle: p)
for i in 0 ..< s.count {
while j > 0 && s[i] != p[j] {
j = next[j-1]
}
if s[i] == p[j] {
j += 1
}
if j == p.count {
return i - p.count + 1
}
}
return -1
}
//前缀表
func getNext(_ next: inout [Int], needle: [Character]) {
var j = 0
next[0] = j
for i in 1 ..< needle.count {
while j>0 && needle[i] != needle[j] {
j = next[j-1]
}
if needle[i] == needle[j] {
j += 1
}
next[i] = j
}
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

55
problems/0053.最大子序和.md
View File

@ -230,6 +230,60 @@ var maxSubArray = function(nums) {
};
```
### C:
贪心：
```c
int maxSubArray(int* nums, int numsSize){
int maxVal = INT_MIN;
int subArrSum = 0;
int i;
for(i = 0; i < numsSize; ++i) {
subArrSum += nums[i];
// 若当前局部和大于之前的最大结果，对结果进行更新
maxVal = subArrSum > maxVal ? subArrSum : maxVal;
// 若当前局部和为负，对结果无益。则从nums[i+1]开始应重新计算。
subArrSum = subArrSum < 0 ? 0 : subArrSum;
}
return maxVal;
}
```
动态规划：
```c
/**
* 解题思路：动态规划：
* 1. dp数组：dp[i]表示从0到i的子序列中最大序列和的值
* 2. 递推公式：dp[i] = max(dp[i-1] + nums[i], nums[i])
若dp[i-1]<0，对最后结果无益。dp[i]则为nums[i]。
* 3. dp数组初始化：dp[0]的最大子数组和为nums[0]
* 4. 推导顺序：从前往后遍历
*/
#define max(a, b) (((a) > (b)) ? (a) : (b))
int maxSubArray(int* nums, int numsSize){
int dp[numsSize];
// dp[0]最大子数组和为nums[0]
dp[0] = nums[0];
// 若numsSize为1，应直接返回nums[0]
int subArrSum = nums[0];
int i;
for(i = 1; i < numsSize; ++i) {
dp[i] = max(dp[i - 1] + nums[i], nums[i]);
// 若dp[i]大于之前记录的最大值，进行更新
if(dp[i] > subArrSum)
subArrSum = dp[i];
}
return subArrSum;
}
```
### TypeScript
**贪心**
@ -267,5 +321,6 @@ function maxSubArray(nums: number[]): number {
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

24
problems/0055.跳跃游戏.md
View File

@ -154,6 +154,30 @@ var canJump = function(nums) {
};
```
### C
```c
#define max(a, b) (((a) > (b)) ? (a) : (b))
bool canJump(int* nums, int numsSize){
int cover = 0;
int i;
// 只可能获取cover范围中的步数，所以i<=cover
for(i = 0; i <= cover; ++i) {
// 更新cover为从i出发能到达的最大值/cover的值中较大值
cover = max(i + nums[i], cover);
// 若更新后cover可以到达最后的元素，返回true
if(cover >= numsSize - 1)
return true;
}
return false;
}
```
### TypeScript
```typescript

2
problems/0093.复原IP地址.md
View File

@ -227,7 +227,7 @@ private:
public:
vector<string> restoreIpAddresses(string s) {
result.clear();
if (s.size() > 12) return result; // 算是剪枝了
if (s.size() < 4 || s.size() > 12) return result; // 算是剪枝了
backtracking(s, 0, 0);
return result;
}

6
problems/0106.从中序与后序遍历序列构造二叉树.md
View File

@ -103,7 +103,7 @@ TreeNode* traversal (vector<int>& inorder, vector<int>& postorder) {
中序数组相对比较好切，找到切割点（后序数组的最后一个元素）在中序数组的位置，然后切割，如下代码中我坚持左闭右开的原则：
```C++
```CPP
// 找到中序遍历的切割点
int delimiterIndex;
for (delimiterIndex = 0; delimiterIndex < inorder.size(); delimiterIndex++) {
@ -130,7 +130,7 @@ vector<int> rightInorder(inorder.begin() + delimiterIndex + 1, inorder.end() );
代码如下：
```
```CPP
// postorder 舍弃末尾元素，因为这个元素就是中间节点，已经用过了
postorder.resize(postorder.size() - 1);
@ -144,7 +144,7 @@ vector<int> rightPostorder(postorder.begin() + leftInorder.size(), postorder.end
接下来可以递归了，代码如下：
```
```CPP
root->left = traversal(leftInorder, leftPostorder);
root->right = traversal(rightInorder, rightPostorder);
```

24
problems/0122.买卖股票的最佳时机II.md
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@ -281,7 +281,7 @@ function maxProfit(prices: number[]): number {
```
C:
贪心：
```c
int maxProfit(int* prices, int pricesSize){
int result = 0;
@ -296,5 +296,27 @@ int maxProfit(int* prices, int pricesSize){
}
```
动态规划：
```c
#define max(a, b) (((a) > (b)) ? (a) : (b))
int maxProfit(int* prices, int pricesSize){
int dp[pricesSize][2];
dp[0][0] = 0 - prices[0];
dp[0][1] = 0;
int i;
for(i = 1; i < pricesSize; ++i) {
// dp[i][0]为i-1天持股的钱数/在第i天用i-1天的钱买入的最大值。
// 若i-1天持股，且第i天买入股票比i-1天持股时更亏，说明应在i-1天时持股
dp[i][0] = max(dp[i-1][0], dp[i-1][1] - prices[i]);
//dp[i][1]为i-1天不持股钱数/在第i天卖出所持股票dp[i-1][0] + prices[i]的最大值
dp[i][1] = max(dp[i-1][1], dp[i-1][0] + prices[i]);
}
// 返回在最后一天不持股时的钱数（将股票卖出后钱最大化）
return dp[pricesSize - 1][1];
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

44
problems/0135.分发糖果.md
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@ -238,6 +238,49 @@ var candy = function(ratings) {
};
```
### C
```c
#define max(a, b) (((a) > (b)) ? (a) : (b))
int *initCandyArr(int size) {
int *candyArr = (int*)malloc(sizeof(int) * size);
int i;
for(i = 0; i < size; ++i)
candyArr[i] = 1;
return candyArr;
}
int candy(int* ratings, int ratingsSize){
// 初始化数组，每个小孩开始至少有一颗糖
int *candyArr = initCandyArr(ratingsSize);
int i;
// 先判断右边是否比左边评分高。若是，右边孩子的糖果为左边孩子+1（candyArr[i] = candyArr[i - 1] + 1)
for(i = 1; i < ratingsSize; ++i) {
if(ratings[i] > ratings[i - 1])
candyArr[i] = candyArr[i - 1] + 1;
}
// 再判断左边评分是否比右边高。
// 若是，左边孩子糖果为右边孩子糖果+1/自己所持糖果最大值。（若糖果已经比右孩子+1多，则不需要更多糖果）
// 举例：ratings为[1, 2, 3, 1]。此时评分为3的孩子在判断右边比左边大后为3，虽然它比最末尾的1(ratings[3])大，但是candyArr[3]为1。所以不必更新candyArr[2]
for(i = ratingsSize - 2; i >= 0; --i) {
if(ratings[i] > ratings[i + 1])
candyArr[i] = max(candyArr[i], candyArr[i + 1] + 1);
}
// 求出糖果之和
int result = 0;
for(i = 0; i < ratingsSize; ++i) {
result += candyArr[i];
}
return result;
}
```
### TypeScript
```typescript
@ -264,6 +307,5 @@ function candy(ratings: number[]): number {
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

28
problems/0143.重排链表.md
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@ -336,7 +336,33 @@ class Solution:
return pre
```
### Go
```go
# 方法三 分割链表
func reorderList(head *ListNode) {
var slow=head
var fast=head
for fast!=nil&&fast.Next!=nil{
slow=slow.Next
fast=fast.Next.Next
} //双指针将链表分为左右两部分
var right =new(ListNode)
for slow!=nil{
temp:=slow.Next
slow.Next=right.Next
right.Next=slow
slow=temp
} //翻转链表右半部分
right=right.Next //right为反转后得右半部分
h:=head
for right.Next!=nil{
temp:=right.Next
right.Next=h.Next
h.Next=right
h=h.Next.Next
right=temp
} //将左右两部分重新组合
}
```
### JavaScript
```javascript

31
problems/0209.长度最小的子数组.md
View File

@ -198,7 +198,7 @@ JavaScript:
var minSubArrayLen = function(target, nums) {
// 长度计算一次
const len = nums.length;
let l = r = sum = 0,
let l = r = sum = 0,
res = len + 1; // 子数组最大不会超过自身
while(r < len) {
sum += nums[r++];
@ -260,12 +260,12 @@ Rust:
```rust
impl Solution {
pub fn min_sub_array_len(target: i32, nums: Vec<i32>) -> i32 {
pub fn min_sub_array_len(target: i32, nums: Vec<i32>) -> i32 {
let (mut result, mut subLength): (i32, i32) = (i32::MAX, 0);
let (mut sum, mut i) = (0, 0);
for (pos, val) in nums.iter().enumerate() {
sum += val;
sum += val;
while sum >= target {
subLength = (pos - i + 1) as i32;
if result > subLength {
@ -364,7 +364,7 @@ int minSubArrayLen(int target, int* nums, int numsSize){
int minLength = INT_MAX;
int sum = 0;
int left = 0, right = 0;
int left = 0, right = 0;
//右边界向右扩展
for(; right < numsSize; ++right) {
sum += nums[right];
@ -380,5 +380,26 @@ int minSubArrayLen(int target, int* nums, int numsSize){
}
```
Kotlin:
```kotlin
class Solution {
fun minSubArrayLen(target: Int, nums: IntArray): Int {
var start = 0
var end = 0
var ret = Int.MAX_VALUE
var count = 0
while (end < nums.size) {
count += nums[end]
while (count >= target) {
ret = if (ret > (end - start + 1)) end - start + 1 else ret
count -= nums[start++]
}
end++
}
return if (ret == Int.MAX_VALUE) 0 else ret
}
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

2
problems/0332.重新安排行程.md
View File

@ -342,7 +342,7 @@ class Solution:
return path
```
### Go
### GO
```go
type pair struct {
target string

29
problems/0376.摆动序列.md
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@ -298,6 +298,35 @@ var wiggleMaxLength = function(nums) {
};
```
### C
**贪心**
```c
int wiggleMaxLength(int* nums, int numsSize){
if(numsSize <= 1)
return numsSize;
int length = 1;
int preDiff , curDiff;
preDiff = curDiff = 0;
for(int i = 0; i < numsSize - 1; ++i) {
// 计算当前i元素与i+1元素差值
curDiff = nums[i+1] - nums[i];
// 若preDiff与curDiff符号不符，则子序列长度+1。更新preDiff的符号
// 若preDiff与curDiff符号一致，当前i元素为连续升序/连续降序子序列的中间元素。不被记录入长度
// 注：当preDiff为0时，curDiff为正或为负都属于符号不同
if((curDiff > 0 && preDiff <= 0) || (preDiff >= 0 && curDiff < 0)) {
preDiff = curDiff;
length++;
}
}
return length;
}
```
### TypeScript
**贪心**

4
problems/0383.赎金信.md
View File

@ -84,6 +84,10 @@ class Solution {
public:
bool canConstruct(string ransomNote, string magazine) {
int record[26] = {0};
//add
if (ransomNote.size() > magazine.size()) {
return false;
}
for (int i = 0; i < magazine.length(); i++) {
// 通过recode数据记录 magazine里各个字符出现次数
record[magazine[i]-'a'] ++;

26
problems/0452.用最少数量的箭引爆气球.md
View File

@ -193,7 +193,7 @@ func min(a,b int) int{
}
return a
}
```
```
### Javascript
```Javascript
@ -214,7 +214,31 @@ var findMinArrowShots = function(points) {
};
```
### TypeScript
```typescript
function findMinArrowShots(points: number[][]): number {
const length: number = points.length;
if (length === 0) return 0;
points.sort((a, b) => a[0] - b[0]);
let resCount: number = 1;
let right: number = points[0][1]; // 右边界
let tempPoint: number[];
for (let i = 1; i < length; i++) {
tempPoint = points[i];
if (tempPoint[0] > right) {
resCount++;
right = tempPoint[1];
} else {
right = Math.min(right, tempPoint[1]);
}
}
return resCount;
};
```
### C
```c
int cmp(const void *a,const void *b)
{

84
problems/0459.重复的子字符串.md
View File

@ -421,5 +421,89 @@ function repeatedSubstringPattern(s: string): boolean {
};
```
Swift:
> 前缀表统一减一
```swift
func repeatedSubstringPattern(_ s: String) -> Bool {
let sArr = Array(s)
let len = s.count
if len == 0 {
return false
}
var next = Array.init(repeating: -1, count: len)
getNext(&next,sArr)
if next.last != -1 && len % (len - (next[len-1] + 1)) == 0{
return true
}
return false
}
func getNext(_ next: inout [Int], _ str:[Character]) {
var j = -1
next[0] = j
for i in 1 ..< str.count {
while j >= 0 && str[j+1] != str[i] {
j = next[j]
}
if str[i] == str[j+1] {
j += 1
}
next[i] = j
}
}
```
> 前缀表统一不减一
```swift
func repeatedSubstringPattern(_ s: String) -> Bool {
let sArr = Array(s)
let len = sArr.count
if len == 0 {
return false
}
var next = Array.init(repeating: 0, count: len)
getNext(&next, sArr)
if next[len-1] != 0 && len % (len - next[len-1]) == 0 {
return true
}
return false
}
// 前缀表不减一
func getNext(_ next: inout [Int], _ sArr:[Character]) {
var j = 0
next[0] = 0
for i in 1 ..< sArr.count {
while j > 0 && sArr[i] != sArr[j] {
j = next[j-1]
}
if sArr[i] == sArr[j] {
j += 1
}
next[i] = j
}
}
```
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

41
problems/1005.K次取反后最大化的数组和.md
View File

@ -211,6 +211,46 @@ var largestSumAfterKNegations = function(nums, k) {
};
```
### C
```c
#define abs(a) (((a) > 0) ? (a) : (-(a)))
// 对数组求和
int sum(int *nums, int numsSize) {
int sum = 0;
int i;
for(i = 0; i < numsSize; ++i) {
sum += nums[i];
}
return sum;
}
int cmp(const void* v1, const void* v2) {
return abs(*(int*)v2) - abs(*(int*)v1);
}
int largestSumAfterKNegations(int* nums, int numsSize, int k){
qsort(nums, numsSize, sizeof(int), cmp);
int i;
for(i = 0; i < numsSize; ++i) {
// 遍历数组，若当前元素<0则将当前元素转变，k--
if(nums[i] < 0 && k > 0) {
nums[i] *= -1;
--k;
}
}
// 若遍历完数组后k还有剩余（此时所有元素应均为正），则将绝对值最小的元素nums[numsSize - 1]变为负
if(k % 2 == 1)
nums[numsSize - 1] *= -1;
return sum(nums, numsSize);
}
```
### TypeScript
```typescript
@ -235,5 +275,6 @@ function largestSumAfterKNegations(nums: number[], k: number): number {
-----------------------
<div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>

8
problems/二叉树的递归遍历.md
View File

@ -371,18 +371,18 @@ C:
```c
//前序遍历：
void preOrderTraversal(struct TreeNode* root, int* ret, int* returnSize) {
void preOrder(struct TreeNode* root, int* ret, int* returnSize) {
if(root == NULL)
return;
ret[(*returnSize)++] = root->val;
preOrderTraverse(root->left, ret, returnSize);
preOrderTraverse(root->right, ret, returnSize);
preOrder(root->left, ret, returnSize);
preOrder(root->right, ret, returnSize);
}
int* preorderTraversal(struct TreeNode* root, int* returnSize){
int* ret = (int*)malloc(sizeof(int) * 100);
*returnSize = 0;
preOrderTraversal(root, ret, returnSize);
preOrder(root, ret, returnSize);
return ret;
}

2
problems/背包问题理论基础完全背包.md
View File

@ -37,7 +37,7 @@
* [动态规划：关于01背包问题，你该了解这些！（滚动数组）](https://programmercarl.com/背包理论基础01背包-2.html)
首先在回顾一下01背包的核心代码
```
```cpp
for(int i = 0; i < weight.size(); i++) { // 遍历物品
for(int j = bagWeight; j >= weight[i]; j--) { // 遍历背包容量
dp[j] = max(dp[j], dp[j - weight[i]] + value[i]);