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93 changes: 30 additions & 63 deletions problems/0093.复原IP地址.md
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## 93.复原IP地址
# 93.复原IP地址

[力扣题目链接](https://leetcode-cn.com/problems/restore-ip-addresses/)

Expand All @@ -19,31 +19,31 @@
例如:"0.1.2.201" 和 "192.168.1.1" 是 有效的 IP 地址,但是 "0.011.255.245"、"192.168.1.312" 和 "192.168@1.1" 是 无效的 IP 地址。

示例 1:
输入:s = "25525511135"
输出:["255.255.11.135","255.255.111.35"]
* 输入:s = "25525511135"
* 输出:["255.255.11.135","255.255.111.35"]

示例 2:
输入:s = "0000"
输出:["0.0.0.0"]
* 输入:s = "0000"
* 输出:["0.0.0.0"]

示例 3:
输入:s = "1111"
输出:["1.1.1.1"]
* 输入:s = "1111"
* 输出:["1.1.1.1"]

示例 4:
输入:s = "010010"
输出:["0.10.0.10","0.100.1.0"]
* 输入:s = "010010"
* 输出:["0.10.0.10","0.100.1.0"]

示例 5:
输入:s = "101023"
输出:["1.0.10.23","1.0.102.3","10.1.0.23","10.10.2.3","101.0.2.3"]
* 输入:s = "101023"
* 输出:["1.0.10.23","1.0.102.3","10.1.0.23","10.10.2.3","101.0.2.3"]

提示:
0 <= s.length <= 3000
s 仅由数字组成
* 0 <= s.length <= 3000
* s 仅由数字组成


## 思路
# 思路

做这道题目之前,最好先把[131.分割回文串](https://programmercarl.com/0131.分割回文串.html)这个做了。

Expand Down Expand Up @@ -114,7 +114,7 @@ if (pointNum == 3) { // 逗点数量为3时,分隔结束

代码如下:

```
```CPP
for (int i = startIndex; i < s.size(); i++) {
if (isValid(s, startIndex, i)) { // 判断 [startIndex,i] 这个区间的子串是否合法
s.insert(s.begin() + i + 1 , '.'); // 在i的后面插入一个逗点
Expand All @@ -138,7 +138,7 @@ for (int i = startIndex; i < s.size(); i++) {

代码如下:

```
```CPP
// 判断字符串s在左闭又闭区间[start, end]所组成的数字是否合法
bool isValid(const string& s, int start, int end) {
if (start > end) {
Expand Down Expand Up @@ -237,7 +237,7 @@ public:
```

## 总结
# 总结

[131.分割回文串](https://programmercarl.com/0131.分割回文串.html)中我列举的分割字符串的难点,本题都覆盖了。

Expand All @@ -249,9 +249,9 @@ public:



## 其他语言版本
# 其他语言版本

java 版本:
## java

```java
class Solution {
Expand Down Expand Up @@ -308,7 +308,9 @@ class Solution {
}
```

python版本:
## python

python2:
```python
class Solution:
def restoreIpAddresses(self, s: str) -> List[str]:
Expand Down Expand Up @@ -338,6 +340,8 @@ class Solution:
backtrack(s, 0)
return res
```

python3:
```python
class Solution(object):
def restoreIpAddresses(self, s):
Expand Down Expand Up @@ -366,47 +370,8 @@ class Solution(object):
return ans```
```

```python3
class Solution:
def __init__(self) -> None:
self.s = ""
self.res = []

def isVaild(self, s: str) -> bool:
if len(s) > 1 and s[0] == "0":
return False

if 0 <= int(s) <= 255:
return True

return False

def backTrack(self, path: List[str], start: int) -> None:
if start == len(self.s) and len(path) == 4:
self.res.append(".".join(path))
return

for end in range(start + 1, len(self.s) + 1):
# 剪枝
# 保证切割完,s没有剩余的字符。
if len(self.s) - end > 3 * (4 - len(path) - 1):
continue
if self.isVaild(self.s[start:end]):
# 在参数处,更新状态,实则创建一个新的变量
# 不会影响当前的状态,当前的path变量没有改变
# 因此递归完不用path.pop()
self.backTrack(path + [self.s[start:end]], end)

def restoreIpAddresses(self, s: str) -> List[str]:
# prune
if len(s) > 3 * 4:
return []
self.s = s
self.backTrack([], 0)
return self.res
```

JavaScript:
## JavaScript

```js
/**
Expand Down Expand Up @@ -435,8 +400,10 @@ var restoreIpAddresses = function(s) {
}
};
```
Go:
> 回溯(对于前导 0的IP(特别注意s[startIndex]=='0'的判断,不应该写成s[startIndex]==0,因为s截取出来不是数字))

## Go

回溯(对于前导 0的IP(特别注意s[startIndex]=='0'的判断,不应该写成s[startIndex]==0,因为s截取出来不是数字))

```go
func restoreIpAddresses(s string) []string {
Expand Down Expand Up @@ -476,7 +443,7 @@ func isNormalIp(s string,startIndex,end int)bool{

```

C:
## C
```c
//记录结果
char** result;
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4 changes: 4 additions & 0 deletions problems/其他/参与本项目.md
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git add之前,要git diff 查看一下,本次提交所修改的代码是不是 自己修改的,是否 误删,或者误加的文件。

提交代码,不要使用git push -f 这种命令,要足够了解 -f 意味着什么。


不用非要写出牛逼的代码才能提交PR,只要发现 文章中有任何问题,或者错别字,都欢迎提交PR,成为contributor。
![](https://code-thinking-1253855093.file.myqcloud.com/pics/20210927113149.png)

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