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‎README.md

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -141,9 +141,9 @@
141141

142142
1. [字符串：344.反转字符串](./problems/0344.反转字符串.md)
143143
2. [字符串：541.反转字符串II](./problems/0541.反转字符串II.md)
144-
3. [字符串：替换数字](./problems/kama54.替换数字.md)
144+
3. [字符串：替换数字](./problems/kamacoder/0054.替换数字.md)
145145
4. [字符串：151.翻转字符串里的单词](./problems/0151.翻转字符串里的单词.md)
146-
5. [字符串：右旋字符串](./problems/kama55.右旋字符串.md)
146+
5. [字符串：右旋字符串](./problems/kamacoder/0055.右旋字符串.md)
147147
6. [帮你把KMP算法学个通透](./problems/0028.实现strStr.md)
148148
8. [字符串：459.重复的子字符串](./problems/0459.重复的子字符串.md)
149149
9. [字符串：总结篇！](./problems/字符串总结.md)
@@ -154,7 +154,7 @@
154154

155155
1. [数组：27.移除元素](./problems/0027.移除元素.md)
156156
2. [字符串：344.反转字符串](./problems/0344.反转字符串.md)
157-
3. [字符串：替换数字](./problems/kama54.替换数字.md)
157+
3. [字符串：替换数字](./problems/kamacoder/0054.替换数字.md)
158158
4. [字符串：151.翻转字符串里的单词](./problems/0151.翻转字符串里的单词.md)
159159
5. [链表：206.翻转链表](./problems/0206.翻转链表.md)
160160
6. [链表：19.删除链表的倒数第 N 个结点](./problems/0019.删除链表的倒数第N个节点.md)

‎problems/0001.两数之和.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -341,7 +341,7 @@ impl Solution {
341341
}
342342
```
343343

344-
### Javascript:
344+
### JavaScript:
345345

346346
```javascript
347347
var twoSum = function (nums, target) {

‎problems/0015.三数之和.md

Lines changed: 24 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -34,7 +34,7 @@
3434

3535
### 哈希解法
3636

37-
两层for循环就可以确定 a 和b 的数值了，可以使用哈希法来确定 0-(a+b) 是否在 数组里出现过，其实这个思路是正确的，但是我们有一个非常棘手的问题，就是题目中说的不可以包含重复的三元组。
37+
两层for循环就可以确定 两个数值，可以使用哈希法来确定 第三个数 0-(a+b) 或者 0 - (a + c) 是否在 数组里出现过，其实这个思路是正确的，但是我们有一个非常棘手的问题，就是题目中说的不可以包含重复的三元组。
3838

3939
把符合条件的三元组放进vector中，然后再去重，这样是非常费时的，很容易超时，也是这道题目通过率如此之低的根源所在。
4040

@@ -48,35 +48,41 @@
4848
```CPP
4949
class Solution {
5050
public:
51+
// 在一个数组中找到3个数形成的三元组，它们的和为0，不能重复使用（三数下标互不相同），且三元组不能重复。
52+
// b（存储）== 0-(a+c)（检索）
5153
vector<vector<int>> threeSum(vector<int>& nums) {
5254
vector<vector<int>> result;
5355
sort(nums.begin(), nums.end());
54-
// 找出a + b + c = 0
55-
// a = nums[i], b = nums[j], c = -(a + b)
56+
5657
for (int i = 0; i < nums.size(); i++) {
57-
// 排序之后如果第一个元素已经大于零，那么不可能凑成三元组
58-
if (nums[i] > 0) {
58+
// 如果a是正数，a<b<c，不可能形成和为0的三元组
59+
if (nums[i] > 0)
5960
break;
60-
}
61-
if (i > 0 && nums[i] == nums[i - 1]) { //三元组元素a去重
61+
62+
// [a, a, ...] 如果本轮a和上轮a相同，那么找到的b，c也是相同的，所以去重a
63+
if (i > 0 && nums[i] == nums[i - 1])
6264
continue;
63-
}
65+
66+
// 这个set的作用是存储b
6467
unordered_set<int> set;
65-
for (int j = i + 1; j < nums.size(); j++) {
66-
if (j > i + 2
67-
&& nums[j] == nums[j-1]
68-
&& nums[j-1] == nums[j-2]) { // 三元组元素b去重
68+
69+
for (int k = i + 1; k < nums.size(); k++) {
70+
// 去重b=c时的b和c
71+
if (k > i + 2 && nums[k] == nums[k - 1] && nums[k - 1] == nums[k - 2])
6972
continue;
73+
74+
// a+b+c=0 <=> b=0-(a+c)
75+
int target = 0 - (nums[i] + nums[k]);
76+
if (set.find(target) != set.end()) {
77+
result.push_back({nums[i], target, nums[k]}); // nums[k]成为c
78+
set.erase(target);
7079
}
71-
int c = 0 - (nums[i] + nums[j]);
72-
if (set.find(c) != set.end()) {
73-
result.push_back({nums[i], nums[j], c});
74-
set.erase(c);// 三元组元素c去重
75-
} else {
76-
set.insert(nums[j]);
80+
else {
81+
set.insert(nums[k]); // nums[k]成为b
7782
}
7883
}
7984
}
85+
8086
return result;
8187
}
8288
};

‎problems/0019.删除链表的倒数第N个节点.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -58,7 +58,7 @@
5858

5959
* fast和slow同时移动，直到fast指向末尾，如题：
6060
<img src='https://code-thinking.cdn.bcebos.com/pics/19.%E5%88%A0%E9%99%A4%E9%93%BE%E8%A1%A8%E7%9A%84%E5%80%92%E6%95%B0%E7%AC%ACN%E4%B8%AA%E8%8A%82%E7%82%B92.png' width=600> </img></div>
61-
61+
//图片中有错别词：应该将“只到”改为“直到”
6262
* 删除slow指向的下一个节点，如图：
6363
<img src='https://code-thinking.cdn.bcebos.com/pics/19.%E5%88%A0%E9%99%A4%E9%93%BE%E8%A1%A8%E7%9A%84%E5%80%92%E6%95%B0%E7%AC%ACN%E4%B8%AA%E8%8A%82%E7%82%B93.png' width=600> </img></div>
6464

‎problems/0020.有效的括号.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -275,7 +275,7 @@ def is_valid(strs)
275275
end
276276
```
277277

278-
### Javascript:
278+
### JavaScript:
279279

280280
```javascript
281281
var isValid = function (s) {

‎problems/0024.两两交换链表中的节点.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -286,7 +286,7 @@ func swapPairs(head *ListNode) *ListNode {
286286
}
287287
```
288288

289-
### Javascript:
289+
### JavaScript:
290290

291291
```javascript
292292
var swapPairs = function (head) {

‎problems/0027.移除元素.md

Lines changed: 18 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -131,7 +131,24 @@ public:
131131
## 其他语言版本
132132
133133
### Java：
134-
134+
```java
135+
class Solution {
136+
public int removeElement(int[] nums, int val) {
137+
// 暴力法
138+
int n = nums.length;
139+
for (int i = 0; i < n; i++) {
140+
if (nums[i] == val) {
141+
for (int j = i + 1; j < n; j++) {
142+
nums[j - 1] = nums[j];
143+
}
144+
i--;
145+
n--;
146+
}
147+
}
148+
return n;
149+
}
150+
}
151+
```
135152
```java
136153
class Solution {
137154
public int removeElement(int[] nums, int val) {

‎problems/0028.实现strStr.md

Lines changed: 64 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1456,6 +1456,70 @@ public int[] GetNext(string needle)
14561456
}
14571457
```
14581458

1459+
### C:
1460+
1461+
> 前缀表统一右移和减一
1462+
1463+
```c
1464+
1465+
int *build_next(char* needle, int len) {
1466+
1467+
int *next = (int *)malloc(len * sizeof(int));
1468+
assert(next); // 确保分配成功
1469+
1470+
// 初始化next数组
1471+
next[0] = -1; // next[0] 设置为 -1，表示没有有效前缀匹配
1472+
if (len <= 1) { // 如果模式串长度小于等于 1，直接返回
1473+
return next;
1474+
}
1475+
next[1] = 0; // next[1] 设置为 0，表示第一个字符没有公共前后缀
1476+
1477+
// 构建next数组， i 从模式串的第三个字符开始， j 指向当前匹配的最长前缀长度
1478+
int i = 2, j = 0;
1479+
while (i < len) {
1480+
if (needle[i - 1] == needle[j]) {
1481+
j++;
1482+
next[i] = j;
1483+
i++;
1484+
} else if (j > 0) {
1485+
// 如果不匹配且 j > 0， 回退到次长匹配前缀的长度
1486+
j = next[j];
1487+
} else {
1488+
next[i] = 0;
1489+
i++;
1490+
}
1491+
}
1492+
return next;
1493+
}
1494+
1495+
int strStr(char* haystack, char* needle) {
1496+
1497+
int needle_len = strlen(needle);
1498+
int haystack_len = strlen(haystack);
1499+
1500+
int *next = build_next(needle, needle_len);
1501+
1502+
int i = 0, j = 0; // i 指向主串的当前起始位置, j 指向模式串的当前匹配位置
1503+
while (i <= haystack_len - needle_len) {
1504+
if (haystack[i + j] == needle[j]) {
1505+
j++;
1506+
if (j == needle_len) {
1507+
free(next);
1508+
next = NULL
1509+
return i;
1510+
}
1511+
} else {
1512+
i += j - next[j]; // 调整主串的起始位置
1513+
j = j > 0 ? next[j] : 0;
1514+
}
1515+
}
1516+
1517+
free(next);
1518+
next = NULL;
1519+
return -1;
1520+
}
1521+
```
1522+
14591523
<p align="center">
14601524
<a href="https://programmercarl.com/other/kstar.html" target="_blank">
14611525
<img src="../pics/网站星球宣传海报.jpg" width="1000"/>

‎problems/0037.解数独.md

Lines changed: 51 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -366,40 +366,56 @@ class Solution:
366366
"""
367367
Do not return anything, modify board in-place instead.
368368
"""
369-
self.backtracking(board)
370-
371-
def backtracking(self, board: List[List[str]]) -> bool:
372-
# 若有解，返回True；若无解，返回False
373-
for i in range(len(board)): # 遍历行
374-
for j in range(len(board[0])): # 遍历列
375-
# 若空格内已有数字，跳过
376-
if board[i][j] != '.': continue
377-
for k in range(1, 10):
378-
if self.is_valid(i, j, k, board):
379-
board[i][j] = str(k)
380-
if self.backtracking(board): return True
381-
board[i][j] = '.'
382-
# 若数字1-9都不能成功填入空格，返回False无解
383-
return False
384-
return True # 有解
385-
386-
def is_valid(self, row: int, col: int, val: int, board: List[List[str]]) -> bool:
387-
# 判断同一行是否冲突
388-
for i in range(9):
389-
if board[row][i] == str(val):
390-
return False
391-
# 判断同一列是否冲突
392-
for j in range(9):
393-
if board[j][col] == str(val):
394-
return False
395-
# 判断同一九宫格是否有冲突
396-
start_row = (row // 3) * 3
397-
start_col = (col // 3) * 3
398-
for i in range(start_row, start_row + 3):
399-
for j in range(start_col, start_col + 3):
400-
if board[i][j] == str(val):
401-
return False
402-
return True
369+
row_used = [set() for _ in range(9)]
370+
col_used = [set() for _ in range(9)]
371+
box_used = [set() for _ in range(9)]
372+
for row in range(9):
373+
for col in range(9):
374+
num = board[row][col]
375+
if num == ".":
376+
continue
377+
row_used[row].add(num)
378+
col_used[col].add(num)
379+
box_used[(row // 3) * 3 + col // 3].add(num)
380+
self.backtracking(0, 0, board, row_used, col_used, box_used)
381+
382+
def backtracking(
383+
self,
384+
row: int,
385+
col: int,
386+
board: List[List[str]],
387+
row_used: List[List[int]],
388+
col_used: List[List[int]],
389+
box_used: List[List[int]],
390+
) -> bool:
391+
if row == 9:
392+
return True
393+
394+
next_row, next_col = (row, col + 1) if col < 8 else (row + 1, 0)
395+
if board[row][col] != ".":
396+
return self.backtracking(
397+
next_row, next_col, board, row_used, col_used, box_used
398+
)
399+
400+
for num in map(str, range(1, 10)):
401+
if (
402+
num not in row_used[row]
403+
and num not in col_used[col]
404+
and num not in box_used[(row // 3) * 3 + col // 3]
405+
):
406+
board[row][col] = num
407+
row_used[row].add(num)
408+
col_used[col].add(num)
409+
box_used[(row // 3) * 3 + col // 3].add(num)
410+
if self.backtracking(
411+
next_row, next_col, board, row_used, col_used, box_used
412+
):
413+
return True
414+
board[row][col] = "."
415+
row_used[row].remove(num)
416+
col_used[col].remove(num)
417+
box_used[(row // 3) * 3 + col // 3].remove(num)
418+
return False
403419
```
404420

405421
### Go
@@ -460,7 +476,7 @@ func isvalid(row, col int, k byte, board [][]byte) bool {
460476

461477

462478

463-
### Javascript
479+
### JavaScript
464480

465481
```Javascript
466482
var solveSudoku = function(board) {

‎problems/0045.跳跃游戏II.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -374,7 +374,7 @@ func max(a, b int) int {
374374
}
375375
```
376376

377-
### Javascript
377+
### JavaScript
378378

379379
```Javascript
380380
var jump = function(nums) {

‎problems/0046.全排列.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -272,7 +272,7 @@ func dfs(nums []int, cur int) {
272272
}
273273
```
274274

275-
### Javascript
275+
### JavaScript
276276

277277
```js
278278

‎problems/0047.全排列II.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -283,7 +283,7 @@ func dfs(nums []int, cur int) {
283283
}
284284
```
285285

286-
### Javascript
286+
### JavaScript
287287

288288
```javascript
289289
var permuteUnique = function (nums) {

‎problems/0051.N皇后.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -451,7 +451,7 @@ func isValid(n, row, col int, chessboard [][]string) bool {
451451
```
452452

453453

454-
### Javascript
454+
### JavaScript
455455
```Javascript
456456
/**
457457
* @param {number} n

‎problems/0053.最大子序和.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -326,7 +326,7 @@ pub fn max_sub_array(nums: Vec<i32>) -> i32 {
326326
}
327327
```
328328

329-
### Javascript:
329+
### JavaScript:
330330

331331
```Javascript
332332
var maxSubArray = function(nums) {

‎problems/0054.螺旋矩阵.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -260,7 +260,7 @@ class Solution {
260260
}
261261
```
262262

263-
### Javascript
263+
### JavaScript
264264
```
265265
/**
266266
* @param {number[][]} matrix

‎problems/0055.跳跃游戏.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -183,7 +183,7 @@ func max(a, b int ) int {
183183
}
184184
```
185185

186-
### Javascript
186+
### JavaScript
187187

188188
```Javascript
189189
var canJump = function(nums) {

‎problems/0056.合并区间.md

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -215,7 +215,7 @@ func max56(a, b int) int {
215215
```
216216

217217

218-
### Javascript
218+
### JavaScript
219219
```javascript
220220
var merge = function (intervals) {
221221
intervals.sort((a, b) => a[0] - b[0]);

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