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feat: add solutions to lc problems: No.3210~3212 (#3219)
* No.3210.Find the Encrypted String * No.3211.Generate Binary Strings Without Adjacent Zeros * No.3212.Count Submatrices With Equal Frequency of X and Y
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‎solution/0000-0099/0017.Letter Combinations of a Phone Number/README.md

+8-8
Original file line numberDiff line numberDiff line change
@@ -165,13 +165,13 @@ func letterCombinations(digits string) []string {
165165

166166
```ts
167167
function letterCombinations(digits: string): string[] {
168-
if (digits.length == 0) {
168+
if (digits.length === 0) {
169169
return [];
170170
}
171171
const ans: string[] = [''];
172172
const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
173173
for (const i of digits) {
174-
const s = d[parseInt(i) - 2];
174+
const s = d[+i - 2];
175175
const t: string[] = [];
176176
for (const a of ans) {
177177
for (const b of s) {
@@ -218,13 +218,13 @@ impl Solution {
218218
* @return {string[]}
219219
*/
220220
var letterCombinations = function (digits) {
221-
if (digits.length == 0) {
221+
if (digits.length === 0) {
222222
return [];
223223
}
224224
const ans = [''];
225225
const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
226226
for (const i of digits) {
227-
const s = d[parseInt(i) - 2];
227+
const s = d[+i - 2];
228228
const t = [];
229229
for (const a of ans) {
230230
for (const b of s) {
@@ -392,7 +392,7 @@ func letterCombinations(digits string) (ans []string) {
392392

393393
```ts
394394
function letterCombinations(digits: string): string[] {
395-
if (digits.length == 0) {
395+
if (digits.length === 0) {
396396
return [];
397397
}
398398
const ans: string[] = [];
@@ -403,7 +403,7 @@ function letterCombinations(digits: string): string[] {
403403
ans.push(t.join(''));
404404
return;
405405
}
406-
const s = d[parseInt(digits[i]) - 2];
406+
const s = d[+digits[i] - 2];
407407
for (const c of s) {
408408
t.push(c);
409409
dfs(i + 1);
@@ -453,7 +453,7 @@ impl Solution {
453453
* @return {string[]}
454454
*/
455455
var letterCombinations = function (digits) {
456-
if (digits.length == 0) {
456+
if (digits.length === 0) {
457457
return [];
458458
}
459459
const ans = [];
@@ -464,7 +464,7 @@ var letterCombinations = function (digits) {
464464
ans.push(t.join(''));
465465
return;
466466
}
467-
const s = d[parseInt(digits[i]) - 2];
467+
const s = d[+digits[i] - 2];
468468
for (const c of s) {
469469
t.push(c);
470470
dfs(i + 1);

‎solution/0000-0099/0017.Letter Combinations of a Phone Number/README_EN.md

+8-8
Original file line numberDiff line numberDiff line change
@@ -161,13 +161,13 @@ func letterCombinations(digits string) []string {
161161

162162
```ts
163163
function letterCombinations(digits: string): string[] {
164-
if (digits.length == 0) {
164+
if (digits.length === 0) {
165165
return [];
166166
}
167167
const ans: string[] = [''];
168168
const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
169169
for (const i of digits) {
170-
const s = d[parseInt(i) - 2];
170+
const s = d[+i - 2];
171171
const t: string[] = [];
172172
for (const a of ans) {
173173
for (const b of s) {
@@ -214,13 +214,13 @@ impl Solution {
214214
* @return {string[]}
215215
*/
216216
var letterCombinations = function (digits) {
217-
if (digits.length == 0) {
217+
if (digits.length === 0) {
218218
return [];
219219
}
220220
const ans = [''];
221221
const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
222222
for (const i of digits) {
223-
const s = d[parseInt(i) - 2];
223+
const s = d[+i - 2];
224224
const t = [];
225225
for (const a of ans) {
226226
for (const b of s) {
@@ -388,7 +388,7 @@ func letterCombinations(digits string) (ans []string) {
388388

389389
```ts
390390
function letterCombinations(digits: string): string[] {
391-
if (digits.length == 0) {
391+
if (digits.length === 0) {
392392
return [];
393393
}
394394
const ans: string[] = [];
@@ -399,7 +399,7 @@ function letterCombinations(digits: string): string[] {
399399
ans.push(t.join(''));
400400
return;
401401
}
402-
const s = d[parseInt(digits[i]) - 2];
402+
const s = d[+digits[i] - 2];
403403
for (const c of s) {
404404
t.push(c);
405405
dfs(i + 1);
@@ -449,7 +449,7 @@ impl Solution {
449449
* @return {string[]}
450450
*/
451451
var letterCombinations = function (digits) {
452-
if (digits.length == 0) {
452+
if (digits.length === 0) {
453453
return [];
454454
}
455455
const ans = [];
@@ -460,7 +460,7 @@ var letterCombinations = function (digits) {
460460
ans.push(t.join(''));
461461
return;
462462
}
463-
const s = d[parseInt(digits[i]) - 2];
463+
const s = d[+digits[i] - 2];
464464
for (const c of s) {
465465
t.push(c);
466466
dfs(i + 1);

‎solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution.js

+2-2
Original file line numberDiff line numberDiff line change
@@ -3,13 +3,13 @@
33
* @return {string[]}
44
*/
55
var letterCombinations = function (digits) {
6-
if (digits.length == 0) {
6+
if (digits.length === 0) {
77
return [];
88
}
99
const ans = [''];
1010
const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
1111
for (const i of digits) {
12-
const s = d[parseInt(i) - 2];
12+
const s = d[+i - 2];
1313
const t = [];
1414
for (const a of ans) {
1515
for (const b of s) {

‎solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution.ts

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,11 @@
11
function letterCombinations(digits: string): string[] {
2-
if (digits.length == 0) {
2+
if (digits.length === 0) {
33
return [];
44
}
55
const ans: string[] = [''];
66
const d = ['abc', 'def', 'ghi', 'jkl', 'mno', 'pqrs', 'tuv', 'wxyz'];
77
for (const i of digits) {
8-
const s = d[parseInt(i) - 2];
8+
const s = d[+i - 2];
99
const t: string[] = [];
1010
for (const a of ans) {
1111
for (const b of s) {

‎solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution2.js

+2-2
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
* @return {string[]}
44
*/
55
var letterCombinations = function (digits) {
6-
if (digits.length == 0) {
6+
if (digits.length === 0) {
77
return [];
88
}
99
const ans = [];
@@ -14,7 +14,7 @@ var letterCombinations = function (digits) {
1414
ans.push(t.join(''));
1515
return;
1616
}
17-
const s = d[parseInt(digits[i]) - 2];
17+
const s = d[+digits[i] - 2];
1818
for (const c of s) {
1919
t.push(c);
2020
dfs(i + 1);

‎solution/0000-0099/0017.Letter Combinations of a Phone Number/Solution2.ts

+2-2
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
function letterCombinations(digits: string): string[] {
2-
if (digits.length == 0) {
2+
if (digits.length === 0) {
33
return [];
44
}
55
const ans: string[] = [];
@@ -10,7 +10,7 @@ function letterCombinations(digits: string): string[] {
1010
ans.push(t.join(''));
1111
return;
1212
}
13-
const s = d[parseInt(digits[i]) - 2];
13+
const s = d[+digits[i] - 2];
1414
for (const c of s) {
1515
t.push(c);
1616
dfs(i + 1);

‎solution/0700-0799/0724.Find Pivot Index/README.md

+3-3
Original file line numberDiff line numberDiff line change
@@ -77,13 +77,13 @@ tags:
7777

7878
### 方法一：前缀和
7979

80-
我们定义变量 $left$ 表示数组 `nums` 中下标 $i$ 左侧元素之和，变量 $right$ 表示数组 `nums` 中下标 $i$ 右侧元素之和。初始时 $left = 0$, $right = \sum_{i = 0}^{n - 1} nums[i]$。
80+
我们定义变量 $left$ 表示数组 $\textit{nums}$ 中下标 $i$ 左侧元素之和，变量 $right$ 表示数组 $\textit{nums}$ 中下标 $i$ 右侧元素之和。初始时 $left = 0$, $right = \sum_{i = 0}^{n - 1} nums[i]$。
8181

82-
遍历数组 `nums`，对于当前遍历到的数字 $x$，我们更新 $right = right - x$，此时如果 $left=right$，说明当前下标 $i$ 就是中间位置，直接返回即可。否则，我们更新 $left = left + x$，继续遍历下一个数字。
82+
遍历数组 $\textit{nums}$，对于当前遍历到的数字 $x$，我们更新 $right = right - x$，此时如果 $left=right$，说明当前下标 $i$ 就是中间位置，直接返回即可。否则，我们更新 $left = left + x$，继续遍历下一个数字。
8383

8484
遍历结束，如果没有找到中间位置，返回 $-1$。
8585

86-
时间复杂度 $O(n)$，空间复杂度 $O(1)$。其中 $n$ 为数组 `nums` 的长度。
86+
时间复杂度 $O(n)$，空间复杂度 $O(1)$。其中 $n$ 为数组 $\textit{nums}$ 的长度。
8787

8888
相似题目：
8989

‎solution/0700-0799/0724.Find Pivot Index/README_EN.md

+14-1
Original file line numberDiff line numberDiff line change
@@ -73,7 +73,20 @@ Right sum = nums[1] + nums[2] = 1 + -1 = 0
7373

7474
<!-- solution:start -->
7575

76-
### Solution 1
76+
### Solution 1: Prefix Sum
77+
78+
We define a variable $left$ to represent the sum of elements to the left of index $i$ in the array $\textit{nums}$, and a variable $right$ to represent the sum of elements to the right of index $i$ in the array $\textit{nums}$. Initially, $left = 0$, $right = \sum_{i = 0}^{n - 1} nums[i]$.
79+
80+
We traverse the array $\textit{nums}$. For the current number $x$ being traversed, we update $right = right - x$. At this point, if $left = right$, it indicates that the current index $i$ is the middle position, and we can return it directly. Otherwise, we update $left = left + x$ and continue to traverse the next number.
81+
82+
If the middle position is not found by the end of the traversal, return $-1$.
83+
84+
The time complexity is $O(n)$, and the space complexity is $O(1)$. Here, $n$ is the length of the array $\textit{nums}$.
85+
86+
Similar Problems:
87+
88+
- [1991. Find the Middle Index in Array](https://github.com/doocs/leetcode/blob/main/solution/1900-1999/1991.Find%20the%20Middle%20Index%20in%20Array/README_EN.md)
89+
- [2574. Left and Right Sum Differences](https://github.com/doocs/leetcode/blob/main/solution/2500-2599/2574.Left%20and%20Right%20Sum%20Differences/README_EN.md)
7790

7891
<!-- tabs:start -->
7992

‎solution/3200-3299/3210.Find the Encrypted String/README.md

+52-4
Original file line numberDiff line numberDiff line change
@@ -69,32 +69,80 @@ edit_url: https://github.com/doocs/leetcode/edit/main/solution/3200-3299/3210.Fi
6969

7070
<!-- solution:start -->
7171

72-
### 方法一
72+
### 方法一：模拟
73+
74+
我们可以使用模拟的方法，对字符串的第 $i$ 个字符，我们将其替换为字符串的第 $(i + k) \bmod n$ 个字符。
75+
76+
时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 是字符串 $s$ 的长度。
7377

7478
<!-- tabs:start -->
7579

7680
#### Python3
7781

7882
```python
79-
83+
class Solution:
84+
def getEncryptedString(self, s: str, k: int) -> str:
85+
cs = list(s)
86+
n = len(s)
87+
for i in range(n):
88+
cs[i] = s[(i + k) % n]
89+
return "".join(cs)
8090
```
8191

8292
#### Java
8393

8494
```java
85-
95+
class Solution {
96+
public String getEncryptedString(String s, int k) {
97+
char[] cs = s.toCharArray();
98+
int n = cs.length;
99+
for (int i = 0; i < n; ++i) {
100+
cs[i] = s.charAt((i + k) % n);
101+
}
102+
return new String(cs);
103+
}
104+
}
86105
```
87106

88107
#### C++
89108

90109
```cpp
91-
110+
class Solution {
111+
public:
112+
string getEncryptedString(string s, int k) {
113+
int n = s.length();
114+
string cs(n, ' ');
115+
for (int i = 0; i < n; ++i) {
116+
cs[i] = s[(i + k) % n];
117+
}
118+
return cs;
119+
}
120+
};
92121
```
93122
94123
#### Go
95124
96125
```go
126+
func getEncryptedString(s string, k int) string {
127+
cs := []byte(s)
128+
for i := range s {
129+
cs[i] = s[(i+k)%len(s)]
130+
}
131+
return string(cs)
132+
}
133+
```
97134

135+
#### TypeScript
136+
137+
```ts
138+
function getEncryptedString(s: string, k: number): string {
139+
const cs: string[] = [];
140+
const n = s.length;
141+
for (let i = 0; i < n; ++i) {
142+
cs[i] = s[(i + k) % n];
143+
}
144+
return cs.join('');
145+
}
98146
```
99147

100148
<!-- tabs:end -->

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