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Merged
merged 1 commit into from
Aug 25, 2023
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feat: add solutions to lcof2 problem: No.019 #1508

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97 changes: 53 additions & 44 deletions lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/README.md
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Expand Up @@ -46,7 +46,14 @@

<!-- 这里可写通用的实现逻辑 -->

双指针，当 `s[i]` 不等于 `s[j]` 时，分别尝试跳过 `i` 或跳过 `j`。
**方法一：双指针**

我们用两个指针 $i$ 和 $j$ 分别指向字符串 $s$ 的第一个字符和最后一个字符，然后向中间移动指针，每次判断 $s[i]$ 和 $s[j]$ 是否相等：

- 如果 $s[i] = s[j]$，则指针 $i$ 向后移动一位，指针 $j$ 向前移动一位；
- 否则，存在两种情况，即删除字符 $s[i]$ 或者删除字符 $s[j]$，然后判断删除之后的字符串是否是回文字符串。即判断子串 $s[i+1..j]$ 或者子串 $s[i..j-1]$ 是否是回文字符串。

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

<!-- tabs:start -->

Expand All @@ -57,7 +64,7 @@
```python
class Solution:
def validPalindrome(self, s: str) -> bool:
def check(i, j):
def check(i: int, j: int) -> bool:
while i < j:
if s[i] != s[j]:
return False
Expand All @@ -67,7 +74,7 @@ class Solution:
i, j = 0, len(s) - 1
while i < j:
if s[i] != s[j]:
return check(i, j - 1) or check(i + 1, j)
return check(i + 1, j) or check(i, j - 1)
i, j = i + 1, j - 1
return True
```
Expand All @@ -78,16 +85,19 @@ class Solution:

```java
class Solution {
private String s;

public boolean validPalindrome(String s) {
this.s = s;
for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return check(s, i + 1, j) || check(s, i, j - 1);
return check(i + 1, j) || check(i, j - 1);
}
}
return true;
}

private boolean check(String s, int i, int j) {
private boolean check(int i, int j) {
for (; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return false;
Expand All @@ -98,48 +108,26 @@ class Solution {
}
```

### **TypeScript**

```ts
function validPalindrome(s: string): boolean {
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return (
isPalinddrome(s.slice(i, j)) ||
isPalinddrome(s.slice(i + 1, j + 1))
);
}
}
return true;
}

function isPalinddrome(s: string): boolean {
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return false;
}
}
return true;
}
```

### **C++**

```cpp
class Solution {
public:
bool validPalindrome(string s) {
for (int i = 0, j = s.size() - 1; i < j; ++i, --j)
if (s[i] != s[j])
return check(s, i + 1, j) || check(s, i, j - 1);
return 1;
}

bool check(string s, int i, int j) {
for (; i < j; ++i, --j)
if (s[i] != s[j])
return 0;
return 1;
auto check = [&](int i, int j) {
for (; i < j; ++i, --j) {
if (s[i] != s[j]) {
return false;
}
}
return true;
};
for (int i = 0, j = s.size() - 1; i < j; ++i, --j) {
if (s[i] != s[j]) {
return check(i + 1, j) || check(i, j - 1);
}
}
return true;
}
};
```
Expand All @@ -165,6 +153,27 @@ func validPalindrome(s string) bool {
}
```

### **TypeScript**

```ts
function validPalindrome(s: string): boolean {
const check = (i: number, j: number): boolean => {
for (; i < j; ++i, --j) {
if (s[i] !== s[j]) {
return false;
}
}
return true;
};
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
if (s[i] !== s[j]) {
return check(i + 1, j) || check(i, j - 1);
}
}
return true;
}
```

### **JavaScript**

```js
Expand All @@ -173,16 +182,16 @@ func validPalindrome(s string) bool {
* @return {boolean}
*/
var validPalindrome = function (s) {
let check = function (i, j) {
const check = (i, j) => {
for (; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
if (s[i] !== s[j]) {
return false;
}
}
return true;
};
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
if (s[i] !== s[j]) {
return check(i + 1, j) || check(i, j - 1);
}
}
Expand Down
33 changes: 18 additions & 15 deletions lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.cpp
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Original file line number Diff line number Diff line change
@@ -1,16 +1,19 @@
class Solution {
public:
bool validPalindrome(string s) {
for (int i = 0, j = s.size() - 1; i < j; ++i, --j)
if (s[i] != s[j])
return check(s, i + 1, j) || check(s, i, j - 1);
return 1;
}

bool check(string s, int i, int j) {
for (; i < j; ++i, --j)
if (s[i] != s[j])
return 0;
return 1;
}
class Solution {
public:
bool validPalindrome(string s) {
auto check = [&](int i, int j) {
for (; i < j; ++i, --j) {
if (s[i] != s[j]) {
return false;
}
}
return true;
};
for (int i = 0, j = s.size() - 1; i < j; ++i, --j) {
if (s[i] != s[j]) {
return check(i + 1, j) || check(i, j - 1);
}
}
return true;
}
};
39 changes: 21 additions & 18 deletions lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.java
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Original file line number Diff line number Diff line change
@@ -1,19 +1,22 @@
class Solution {
public boolean validPalindrome(String s) {
for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return check(s, i + 1, j) || check(s, i, j - 1);
}
}
return true;
}

private boolean check(String s, int i, int j) {
for (; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return false;
}
}
return true;
}
class Solution {
private String s;

public boolean validPalindrome(String s) {
this.s = s;
for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return check(i + 1, j) || check(i, j - 1);
}
}
return true;
}

private boolean check(int i, int j) {
for (; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return false;
}
}
return true;
}
}
6 changes: 3 additions & 3 deletions lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3,16 +3,16 @@
* @return {boolean}
*/
var validPalindrome = function (s) {
let check = function (i, j) {
const check = (i, j) => {
for (; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
if (s[i] !== s[j]) {
return false;
}
}
return true;
};
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
if (s[i] !== s[j]) {
return check(i + 1, j) || check(i, j - 1);
}
}
Expand Down
30 changes: 15 additions & 15 deletions lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.py
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Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
class Solution:
def validPalindrome(self, s: str) -> bool:
def check(i, j):
while i < j:
if s[i] != s[j]:
return False
i, j = i + 1, j - 1
return True

i, j = 0, len(s) - 1
while i < j:
if s[i] != s[j]:
return check(i, j - 1) or check(i + 1, j)
i, j = i + 1, j - 1
return True
class Solution:
def validPalindrome(self, s: str) -> bool:
def check(i: int, j: int) -> bool:
while i < j:
if s[i] != s[j]:
return False
i, j = i + 1, j - 1
return True
i, j = 0, len(s) - 1
while i < j:
if s[i] != s[j]:
return check(i + 1, j) or check(i, j - 1)
i, j = i + 1, j - 1
return True
24 changes: 10 additions & 14 deletions lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.ts
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Original file line number Diff line number Diff line change
@@ -1,19 +1,15 @@
function validPalindrome(s: string): boolean {
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return (
isPalinddrome(s.slice(i, j)) ||
isPalinddrome(s.slice(i + 1, j + 1))
);
const check = (i: number, j: number): boolean => {
for (; i < j; ++i, --j) {
if (s[i] !== s[j]) {
return false;
}
}
}
return true;
}

function isPalinddrome(s: string): boolean {
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
if (s.charAt(i) != s.charAt(j)) {
return false;
return true;
};
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
if (s[i] !== s[j]) {
return check(i + 1, j) || check(i, j - 1);
}
}
return true;
Expand Down