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feat: add solutions to lcof2 problem: No.019 (doocs#1508)
No.019.最多删除一个字符得到回文
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6 files changed

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‎lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/README.md

Lines changed: 53 additions & 44 deletions
Original file line numberDiff line numberDiff line change
@@ -46,7 +46,14 @@
4646

4747
<!-- 这里可写通用的实现逻辑 -->
4848

49-
双指针，当 `s[i]` 不等于 `s[j]` 时，分别尝试跳过 `i` 或跳过 `j`。
49+
**方法一：双指针**
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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：
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- 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；
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- 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。
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时间复杂度 $O(n)$，其中 $n$ 是字符串 $s$ 的长度。空间复杂度 $O(1)$。
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<!-- tabs:start -->
5259

@@ -57,7 +64,7 @@
5764
```python
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class Solution:
5966
def validPalindrome(self, s: str) -> bool:
60-
def check(i, j):
67+
def check(i: int, j: int) -> bool:
6168
while i < j:
6269
if s[i] != s[j]:
6370
return False
@@ -67,7 +74,7 @@ class Solution:
6774
i, j = 0, len(s) - 1
6875
while i < j:
6976
if s[i] != s[j]:
70-
return check(i, j - 1) or check(i + 1, j)
77+
return check(i + 1, j) or check(i, j - 1)
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i, j = i + 1, j - 1
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return True
7380
```
@@ -78,16 +85,19 @@ class Solution:
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7986
```java
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class Solution {
88+
private String s;
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8190
public boolean validPalindrome(String s) {
91+
this.s = s;
8292
for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
8393
if (s.charAt(i) != s.charAt(j)) {
84-
return check(s, i + 1, j) || check(s, i, j - 1);
94+
return check(i + 1, j) || check(i, j - 1);
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}
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}
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return true;
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}
8999

90-
private boolean check(String s, int i, int j) {
100+
private boolean check(int i, int j) {
91101
for (; i < j; ++i, --j) {
92102
if (s.charAt(i) != s.charAt(j)) {
93103
return false;
@@ -98,48 +108,26 @@ class Solution {
98108
}
99109
```
100110

101-
### **TypeScript**
102-
103-
```ts
104-
function validPalindrome(s: string): boolean {
105-
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
106-
if (s.charAt(i) != s.charAt(j)) {
107-
return (
108-
isPalinddrome(s.slice(i, j)) ||
109-
isPalinddrome(s.slice(i + 1, j + 1))
110-
);
111-
}
112-
}
113-
return true;
114-
}
115-
116-
function isPalinddrome(s: string): boolean {
117-
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
118-
if (s.charAt(i) != s.charAt(j)) {
119-
return false;
120-
}
121-
}
122-
return true;
123-
}
124-
```
125-
126111
### **C++**
127112

128113
```cpp
129114
class Solution {
130115
public:
131116
bool validPalindrome(string s) {
132-
for (int i = 0, j = s.size() - 1; i < j; ++i, --j)
133-
if (s[i] != s[j])
134-
return check(s, i + 1, j) || check(s, i, j - 1);
135-
return 1;
136-
}
137-
138-
bool check(string s, int i, int j) {
139-
for (; i < j; ++i, --j)
140-
if (s[i] != s[j])
141-
return 0;
142-
return 1;
117+
auto check = [&](int i, int j) {
118+
for (; i < j; ++i, --j) {
119+
if (s[i] != s[j]) {
120+
return false;
121+
}
122+
}
123+
return true;
124+
};
125+
for (int i = 0, j = s.size() - 1; i < j; ++i, --j) {
126+
if (s[i] != s[j]) {
127+
return check(i + 1, j) || check(i, j - 1);
128+
}
129+
}
130+
return true;
143131
}
144132
};
145133
```
@@ -165,6 +153,27 @@ func validPalindrome(s string) bool {
165153
}
166154
```
167155

156+
### **TypeScript**
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```ts
159+
function validPalindrome(s: string): boolean {
160+
const check = (i: number, j: number): boolean => {
161+
for (; i < j; ++i, --j) {
162+
if (s[i] !== s[j]) {
163+
return false;
164+
}
165+
}
166+
return true;
167+
};
168+
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
169+
if (s[i] !== s[j]) {
170+
return check(i + 1, j) || check(i, j - 1);
171+
}
172+
}
173+
return true;
174+
}
175+
```
176+
168177
### **JavaScript**
169178

170179
```js
@@ -173,16 +182,16 @@ func validPalindrome(s string) bool {
173182
* @return {boolean}
174183
*/
175184
var validPalindrome = function (s) {
176-
let check = function (i, j) {
185+
const check = (i, j) => {
177186
for (; i < j; ++i, --j) {
178-
if (s.charAt(i) != s.charAt(j)) {
187+
if (s[i] !== s[j]) {
179188
return false;
180189
}
181190
}
182191
return true;
183192
};
184193
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
185-
if (s.charAt(i) != s.charAt(j)) {
194+
if (s[i] !== s[j]) {
186195
return check(i + 1, j) || check(i, j - 1);
187196
}
188197
}

‎lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.cpp

Lines changed: 18 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -1,16 +1,19 @@
1-
class Solution {
2-
public:
3-
bool validPalindrome(string s) {
4-
for (int i = 0, j = s.size() - 1; i < j; ++i, --j)
5-
if (s[i] != s[j])
6-
return check(s, i + 1, j) || check(s, i, j - 1);
7-
return 1;
8-
}
9-
10-
bool check(string s, int i, int j) {
11-
for (; i < j; ++i, --j)
12-
if (s[i] != s[j])
13-
return 0;
14-
return 1;
15-
}
1+
class Solution {
2+
public:
3+
bool validPalindrome(string s) {
4+
auto check = [&](int i, int j) {
5+
for (; i < j; ++i, --j) {
6+
if (s[i] != s[j]) {
7+
return false;
8+
}
9+
}
10+
return true;
11+
};
12+
for (int i = 0, j = s.size() - 1; i < j; ++i, --j) {
13+
if (s[i] != s[j]) {
14+
return check(i + 1, j) || check(i, j - 1);
15+
}
16+
}
17+
return true;
18+
}
1619
};

‎lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.java

Lines changed: 21 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -1,19 +1,22 @@
1-
class Solution {
2-
public boolean validPalindrome(String s) {
3-
for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
4-
if (s.charAt(i) != s.charAt(j)) {
5-
return check(s, i + 1, j) || check(s, i, j - 1);
6-
}
7-
}
8-
return true;
9-
}
10-
11-
private boolean check(String s, int i, int j) {
12-
for (; i < j; ++i, --j) {
13-
if (s.charAt(i) != s.charAt(j)) {
14-
return false;
15-
}
16-
}
17-
return true;
18-
}
1+
class Solution {
2+
private String s;
3+
4+
public boolean validPalindrome(String s) {
5+
this.s = s;
6+
for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
7+
if (s.charAt(i) != s.charAt(j)) {
8+
return check(i + 1, j) || check(i, j - 1);
9+
}
10+
}
11+
return true;
12+
}
13+
14+
private boolean check(int i, int j) {
15+
for (; i < j; ++i, --j) {
16+
if (s.charAt(i) != s.charAt(j)) {
17+
return false;
18+
}
19+
}
20+
return true;
21+
}
1922
}

‎lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.js

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -3,16 +3,16 @@
33
* @return {boolean}
44
*/
55
var validPalindrome = function (s) {
6-
let check = function (i, j) {
6+
const check = (i, j) => {
77
for (; i < j; ++i, --j) {
8-
if (s.charAt(i) != s.charAt(j)) {
8+
if (s[i] !== s[j]) {
99
return false;
1010
}
1111
}
1212
return true;
1313
};
1414
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
15-
if (s.charAt(i) != s.charAt(j)) {
15+
if (s[i] !== s[j]) {
1616
return check(i + 1, j) || check(i, j - 1);
1717
}
1818
}

‎lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.py

Lines changed: 15 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,15 @@
1-
class Solution:
2-
def validPalindrome(self, s: str) -> bool:
3-
def check(i, j):
4-
while i < j:
5-
if s[i] != s[j]:
6-
return False
7-
i, j = i + 1, j - 1
8-
return True
9-
10-
i, j = 0, len(s) - 1
11-
while i < j:
12-
if s[i] != s[j]:
13-
return check(i, j - 1) or check(i + 1, j)
14-
i, j = i + 1, j - 1
15-
return True
1+
class Solution:
2+
def validPalindrome(self, s: str) -> bool:
3+
def check(i: int, j: int) -> bool:
4+
while i < j:
5+
if s[i] != s[j]:
6+
return False
7+
i, j = i + 1, j - 1
8+
return True
9+
10+
i, j = 0, len(s) - 1
11+
while i < j:
12+
if s[i] != s[j]:
13+
return check(i + 1, j) or check(i, j - 1)
14+
i, j = i + 1, j - 1
15+
return True

‎lcof2/剑指 Offer II 019. 最多删除一个字符得到回文/Solution.ts

Lines changed: 10 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1,19 +1,15 @@
11
function validPalindrome(s: string): boolean {
2-
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
3-
if (s.charAt(i) != s.charAt(j)) {
4-
return (
5-
isPalinddrome(s.slice(i, j)) ||
6-
isPalinddrome(s.slice(i + 1, j + 1))
7-
);
2+
const check = (i: number, j: number): boolean => {
3+
for (; i < j; ++i, --j) {
4+
if (s[i] !== s[j]) {
5+
return false;
6+
}
87
}
9-
}
10-
return true;
11-
}
12-
13-
function isPalinddrome(s: string): boolean {
14-
for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
15-
if (s.charAt(i) != s.charAt(j)) {
16-
return false;
8+
return true;
9+
};
10+
for (let i = 0, j = s.length - 1; i < j; ++i, --j) {
11+
if (s[i] !== s[j]) {
12+
return check(i + 1, j) || check(i, j - 1);
1713
}
1814
}
1915
return true;

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