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Merged
yanglbme merged 1 commit into from
Mar 27, 2026
Merged

feat: add solutions for lc No.0645,0647 #5117

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66 changes: 48 additions & 18 deletions solution/0600-0699/0645.Set Mismatch/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -295,29 +295,29 @@ function findErrorNums(nums: number[]): number[] {
#### Rust

```rust
use std::collections::HashMap;

impl Solution {
pub fn find_error_nums(nums: Vec<i32>) -> Vec<i32> {
let mut xs = 0;
for (i, x) in nums.iter().enumerate() {
xs ^= ((i + 1) as i32) ^ x;
}
let mut a = 0;
let lb = xs & -xs;
for (i, x) in nums.iter().enumerate() {
if (((i + 1) as i32) & lb) != 0 {
a ^= (i + 1) as i32;
}
if (*x & lb) != 0 {
a ^= *x;
}
let n = nums.len() as i32;
let mut cnt: HashMap<i32, i32> = HashMap::new();

for &x in &nums {
*cnt.entry(x).or_insert(0) += 1;
}
let b = xs ^ a;
for x in nums.iter() {
if *x == a {
return vec![a, b];

let mut ans = vec![0; 2];

for x in 1..=n {
let c = *cnt.get(&x).unwrap_or(&0);
if c == 2 {
ans[0] = x;
} else if c == 0 {
ans[1] = x;
}
}
vec![b, a]

ans
}
}
```
Expand Down Expand Up @@ -477,6 +477,36 @@ function findErrorNums(nums: number[]): number[] {
}
```

#### Rust

```rust
impl Solution {
pub fn find_error_nums(nums: Vec<i32>) -> Vec<i32> {
let mut xs = 0;
for (i, x) in nums.iter().enumerate() {
xs ^= ((i + 1) as i32) ^ x;
}
let mut a = 0;
let lb = xs & -xs;
for (i, x) in nums.iter().enumerate() {
if (((i + 1) as i32) & lb) != 0 {
a ^= (i + 1) as i32;
}
if (*x & lb) != 0 {
a ^= *x;
}
}
let b = xs ^ a;
for x in nums.iter() {
if *x == a {
return vec![a, b];
}
}
vec![b, a]
}
}
```

<!-- tabs:end -->

<!-- solution:end -->
Expand Down
66 changes: 48 additions & 18 deletions solution/0600-0699/0645.Set Mismatch/README_EN.md
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Original file line number Diff line number Diff line change
Expand Up @@ -286,29 +286,29 @@ function findErrorNums(nums: number[]): number[] {
#### Rust

```rust
use std::collections::HashMap;

impl Solution {
pub fn find_error_nums(nums: Vec<i32>) -> Vec<i32> {
let mut xs = 0;
for (i, x) in nums.iter().enumerate() {
xs ^= ((i + 1) as i32) ^ x;
}
let mut a = 0;
let lb = xs & -xs;
for (i, x) in nums.iter().enumerate() {
if (((i + 1) as i32) & lb) != 0 {
a ^= (i + 1) as i32;
}
if (*x & lb) != 0 {
a ^= *x;
}
let n = nums.len() as i32;
let mut cnt: HashMap<i32, i32> = HashMap::new();

for &x in &nums {
*cnt.entry(x).or_insert(0) += 1;
}
let b = xs ^ a;
for x in nums.iter() {
if *x == a {
return vec![a, b];

let mut ans = vec![0; 2];

for x in 1..=n {
let c = *cnt.get(&x).unwrap_or(&0);
if c == 2 {
ans[0] = x;
} else if c == 0 {
ans[1] = x;
}
}
vec![b, a]

ans
}
}
```
Expand Down Expand Up @@ -468,6 +468,36 @@ function findErrorNums(nums: number[]): number[] {
}
```

#### Rust

```rust
impl Solution {
pub fn find_error_nums(nums: Vec<i32>) -> Vec<i32> {
let mut xs = 0;
for (i, x) in nums.iter().enumerate() {
xs ^= ((i + 1) as i32) ^ x;
}
let mut a = 0;
let lb = xs & -xs;
for (i, x) in nums.iter().enumerate() {
if (((i + 1) as i32) & lb) != 0 {
a ^= (i + 1) as i32;
}
if (*x & lb) != 0 {
a ^= *x;
}
}
let b = xs ^ a;
for x in nums.iter() {
if *x == a {
return vec![a, b];
}
}
vec![b, a]
}
}
```

<!-- tabs:end -->

<!-- solution:end -->
Expand Down
36 changes: 18 additions & 18 deletions solution/0600-0699/0645.Set Mismatch/Solution2.rs
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Original file line number Diff line number Diff line change
@@ -1,25 +1,25 @@
use std::collections::HashMap;

impl Solution {
pub fn find_error_nums(nums: Vec<i32>) -> Vec<i32> {
let mut xs = 0;
for (i, x) in nums.iter().enumerate() {
xs ^= ((i + 1) as i32) ^ x;
let n = nums.len() as i32;
let mut cnt: HashMap<i32, i32> = HashMap::new();

for &x in &nums {
*cnt.entry(x).or_insert(0) += 1;
}
let mut a = 0;
let lb = xs & -xs;
for (i, x) in nums.iter().enumerate() {
if (((i + 1) as i32) & lb) != 0 {
a ^= (i + 1) as i32;
}
if (*x & lb) != 0 {
a ^= *x;
}
}
let b = xs ^ a;
for x in nums.iter() {
if *x == a {
return vec![a, b];

let mut ans = vec![0; 2];

for x in 1..=n {
let c = *cnt.get(&x).unwrap_or(&0);
if c == 2 {
ans[0] = x;
} else if c == 0 {
ans[1] = x;
}
}
vec![b, a]

ans
}
}
25 changes: 25 additions & 0 deletions solution/0600-0699/0645.Set Mismatch/Solution3.rs
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Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
impl Solution {
pub fn find_error_nums(nums: Vec<i32>) -> Vec<i32> {
let mut xs = 0;
for (i, x) in nums.iter().enumerate() {
xs ^= ((i + 1) as i32) ^ x;
}
let mut a = 0;
let lb = xs & -xs;
for (i, x) in nums.iter().enumerate() {
if (((i + 1) as i32) & lb) != 0 {
a ^= (i + 1) as i32;
}
if (*x & lb) != 0 {
a ^= *x;
}
}
let b = xs ^ a;
for x in nums.iter() {
if *x == a {
return vec![a, b];
}
}
vec![b, a]
}
}
130 changes: 128 additions & 2 deletions solution/0600-0699/0647.Palindromic Substrings/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,9 @@ tags:

### 方法一：从中心向两侧扩展回文串

时间复杂度 $O(n^2)$，其中 $n$ 是字符串 `s` 的长度。
我们可以枚举回文串的中心位置，然后向两侧扩展，统计回文串的数量。对于长度为 $n$ 的字符串，回文串的中心位置共有 $2n-1$ 个（包括奇数长度和偶数长度的回文串）。对于每个中心位置，我们向两侧扩展，直到不满足回文串的条件为止，统计回文串的数量。

时间复杂度 $O(n^2)$，其中 $n$ 是字符串 $s$ 的长度。空间复杂度 $O(1)$。

<!-- tabs:start -->

Expand Down Expand Up @@ -166,7 +168,7 @@ var countSubstrings = function (s) {

在 Manacher 算法的计算过程中，用 $p[i]-1$ 表示以第 $i$ 位为中心的最大回文长度，以第 $i$ 位为中心的回文串数量为 $\left \lceil \frac{p[i]-1}{2} \right \rceil$。
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Copilot AI Mar 27, 2026

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这里的“最大回文长度”表述容易引起歧义：本实现里 p[i] 是在插入分隔符后的变换字符串上的回文半径（radius），不等同于原字符串中的长度。建议注明这是变换字符串上的半径/扩展长度，并说明与代码里 ans += p[i] / 2（或 floor(p[i]/2)）的对应关系，避免读者误解。

Suggested change
在 Manacher 算法的计算过程中，用 $p[i]-1$ 表示以第 $i$ 位为中心的最大回文长度，以第 $i$ 位为中心的回文串数量为 $\left \lceil \frac{p[i]-1}{2} \right \rceil$。
在 Manacher 算法中，我们先构造插入分隔符后的变换字符串 `t`，此时 `p[i]` 表示在字符串 `t` 上以第 `i` 位为中心的回文半径（radius，至少为 1，单位是「变换串中的字符数」）。对应到原字符串上，以第 `i` 位为中心所能产生的回文子串数量正好是 `p[i] // 2`，这也是代码中 `ans += p[i] // 2` 的含义。

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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。
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。

<!-- tabs:start -->

Expand Down Expand Up @@ -221,6 +223,130 @@ class Solution {
}
```

#### C++

```cpp
class Solution {
public:
int countSubstrings(string s) {
string t = "^#";
for (char c : s) {
t += c;
t += '#';
}
t += "$";

int n = t.size();
vector<int> p(n, 0);
int pos = 0, maxRight = 0;
int ans = 0;

for (int i = 1; i < n - 1; ++i) {
if (maxRight > i) {
p[i] = min(maxRight - i, p[2 * pos - i]);
} else {
p[i] = 1;
}

while (t[i - p[i]] == t[i + p[i]]) {
++p[i];
}

if (i + p[i] > maxRight) {
maxRight = i + p[i];
pos = i;
}

ans += p[i] / 2;
}

return ans;
}
};
```

#### Go

```go
func countSubstrings(s string) int {
t := "^#"
for _, c := range s {
t += string(c)
t += "#"
}
t += "$"

n := len(t)
p := make([]int, n)
pos, maxRight := 0, 0
ans := 0

for i := 1; i < n-1; i++ {
if maxRight > i {
mirror := 2*pos - i
if p[mirror] < maxRight-i {
p[i] = p[mirror]
} else {
p[i] = maxRight - i
}
} else {
p[i] = 1
}

for t[i-p[i]] == t[i+p[i]] {
p[i]++
}

if i+p[i] > maxRight {
maxRight = i + p[i]
pos = i
}

ans += p[i] / 2
}

return ans
}
```

#### TypeScript

```ts
function countSubstrings(s: string): number {
let t = "^#";
for (const c of s) {
t += c + "#";
}
t += "$";

const n = t.length;
const p: number[] = new Array(n).fill(0);
let pos = 0, maxRight = 0;
let ans = 0;

for (let i = 1; i < n - 1; i++) {
if (maxRight > i) {
p[i] = Math.min(maxRight - i, p[2 * pos - i]);
} else {
p[i] = 1;
}

while (t[i - p[i]] === t[i + p[i]]) {
p[i]++;
}

if (i + p[i] > maxRight) {
maxRight = i + p[i];
pos = i;
}

ans += Math.floor(p[i] / 2);
}

return ans;
}
```

<!-- tabs:end -->

<!-- solution:end -->
Expand Down
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