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feat: add solutions to lc/lcof2 problems
lc No.0093 & lcof2 No.087. Restore IP Addresses
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‎lcof2/剑指 Offer II 087. 复原 IP/README.md

+111-2
Original file line numberDiff line numberDiff line change
@@ -60,27 +60,136 @@
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<p><meta charset="UTF-8" />注意：本题与主站 93&nbsp;题相同：<a href="https://leetcode-cn.com/problems/restore-ip-addresses/">https://leetcode-cn.com/problems/restore-ip-addresses/</a>&nbsp;</p>
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6463
## 解法
6564

6665
<!-- 这里可写通用的实现逻辑 -->
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DFS。
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6869
<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
75-
76+
class Solution:
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def restoreIpAddresses(self, s: str) -> List[str]:
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ans = []
79+
80+
def check(s):
81+
if not (0 <= int(s) <= 255):
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return False
83+
if s[0] == '0' and len(s) > 1:
84+
return False
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return True
86+
87+
def dfs(s, t):
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if len(t) == 4:
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if not s:
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ans.append('.'.join(t))
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return
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for i in range(1, min(4, len(s) + 1)):
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if check(s[:i]):
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t.append(s[:i])
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dfs(s[i:], t)
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t.pop()
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dfs(s, [])
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return ans
76100
```
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78102
### **Java**
79103

80104
<!-- 这里可写当前语言的特殊实现逻辑 -->
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82106
```java
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class Solution {
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private List<String> ans;
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public List<String> restoreIpAddresses(String s) {
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ans = new ArrayList<>();
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dfs(s, new ArrayList<>());
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return ans;
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}
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private void dfs(String s, List<String> t) {
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if (t.size() == 4) {
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if ("".equals(s)) {
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ans.add(String.join(".", t));
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}
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return;
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}
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for (int i = 1; i < Math.min(4, s.length() + 1); ++i) {
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String c = s.substring(0, i);
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if (check(c)) {
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t.add(c);
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dfs(s.substring(i), t);
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t.remove(t.size() - 1);
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}
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}
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}
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private boolean check(String s) {
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if ("".equals(s)) {
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return false;
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}
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int num = Integer.parseInt(s);
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if (num > 255) {
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return false;
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}
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if (s.charAt(0) == '0' && s.length() > 1) {
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return false;
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}
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return true;
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}
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}
147+
```
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149+
### **C++**
150+
151+
```cpp
152+
class Solution {
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public:
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vector<string> restoreIpAddresses(string s) {
155+
vector<string> ans;
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vector<string> t;
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dfs(s, t, ans);
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return ans;
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}
160+
161+
void dfs(string s, vector<string>& t, vector<string>& ans) {
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if (t.size() == 4)
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{
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if (s == "")
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{
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string p = "";
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for (auto e : t) p += e + ".";
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p.pop_back();
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ans.push_back(p);
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}
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return;
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}
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for (int i = 1; i < min(4, (int) s.size() + 1); ++i)
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{
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string c = s.substr(0, i);
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if (check(c))
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{
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t.push_back(c);
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dfs(s.substr(i, s.size() - i), t, ans);
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t.pop_back();
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}
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}
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}
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bool check(string s) {
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if (s == "") return false;
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int num = stoi(s);
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if (num > 255) return false;
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if (s[0] == '0' && s.size() > 1) return false;
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return true;
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}
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};
84193
```
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86195
### **...**

‎lcof2/剑指 Offer II 087. 复原 IP/Solution.cpp

+41
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,41 @@
1+
class Solution {
2+
public:
3+
vector<string> restoreIpAddresses(string s) {
4+
vector<string> ans;
5+
vector<string> t;
6+
dfs(s, t, ans);
7+
return ans;
8+
}
9+
10+
void dfs(string s, vector<string>& t, vector<string>& ans) {
11+
if (t.size() == 4)
12+
{
13+
if (s == "")
14+
{
15+
string p = "";
16+
for (auto e : t) p += e + ".";
17+
p.pop_back();
18+
ans.push_back(p);
19+
}
20+
return;
21+
}
22+
for (int i = 1; i < min(4, (int) s.size() + 1); ++i)
23+
{
24+
string c = s.substr(0, i);
25+
if (check(c))
26+
{
27+
t.push_back(c);
28+
dfs(s.substr(i, s.size() - i), t, ans);
29+
t.pop_back();
30+
}
31+
}
32+
}
33+
34+
bool check(string s) {
35+
if (s == "") return false;
36+
int num = stoi(s);
37+
if (num > 255) return false;
38+
if (s[0] == '0' && s.size() > 1) return false;
39+
return true;
40+
}
41+
};

‎lcof2/剑指 Offer II 087. 复原 IP/Solution.java

+40
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
1+
class Solution {
2+
private List<String> ans;
3+
4+
public List<String> restoreIpAddresses(String s) {
5+
ans = new ArrayList<>();
6+
dfs(s, new ArrayList<>());
7+
return ans;
8+
}
9+
10+
private void dfs(String s, List<String> t) {
11+
if (t.size() == 4) {
12+
if ("".equals(s)) {
13+
ans.add(String.join(".", t));
14+
}
15+
return;
16+
}
17+
for (int i = 1; i < Math.min(4, s.length() + 1); ++i) {
18+
String c = s.substring(0, i);
19+
if (check(c)) {
20+
t.add(c);
21+
dfs(s.substring(i), t);
22+
t.remove(t.size() - 1);
23+
}
24+
}
25+
}
26+
27+
private boolean check(String s) {
28+
if ("".equals(s)) {
29+
return false;
30+
}
31+
int num = Integer.parseInt(s);
32+
if (num > 255) {
33+
return false;
34+
}
35+
if (s.charAt(0) == '0' && s.length() > 1) {
36+
return false;
37+
}
38+
return true;
39+
}
40+
}

‎lcof2/剑指 Offer II 087. 复原 IP/Solution.py

+24
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
class Solution:
2+
def restoreIpAddresses(self, s: str) -> List[str]:
3+
ans = []
4+
5+
def check(s):
6+
if not (0 <= int(s) <= 255):
7+
return False
8+
if s[0] == '0' and len(s) > 1:
9+
return False
10+
return True
11+
12+
def dfs(s, t):
13+
if len(t) == 4:
14+
if not s:
15+
ans.append('.'.join(t))
16+
return
17+
for i in range(1, min(4, len(s) + 1)):
18+
if check(s[:i]):
19+
t.append(s[:i])
20+
dfs(s[i:], t)
21+
t.pop()
22+
23+
dfs(s, [])
24+
return ans

‎solution/0000-0099/0093.Restore IP Addresses/README.md

+111-2
Original file line numberDiff line numberDiff line change
@@ -58,27 +58,136 @@
5858
<li><code>s</code> 仅由数字组成</li>
5959
</ul>
6060

61-
6261
## 解法
6362

6463
<!-- 这里可写通用的实现逻辑 -->
6564

65+
DFS。
66+
6667
<!-- tabs:start -->
6768

6869
### **Python3**
6970

7071
<!-- 这里可写当前语言的特殊实现逻辑 -->
7172

7273
```python
73-
74+
class Solution:
75+
def restoreIpAddresses(self, s: str) -> List[str]:
76+
ans = []
77+
78+
def check(s):
79+
if not (0 <= int(s) <= 255):
80+
return False
81+
if s[0] == '0' and len(s) > 1:
82+
return False
83+
return True
84+
85+
def dfs(s, t):
86+
if len(t) == 4:
87+
if not s:
88+
ans.append('.'.join(t))
89+
return
90+
for i in range(1, min(4, len(s) + 1)):
91+
if check(s[:i]):
92+
t.append(s[:i])
93+
dfs(s[i:], t)
94+
t.pop()
95+
96+
dfs(s, [])
97+
return ans
7498
```
7599

76100
### **Java**
77101

78102
<!-- 这里可写当前语言的特殊实现逻辑 -->
79103

80104
```java
105+
class Solution {
106+
private List<String> ans;
107+
108+
public List<String> restoreIpAddresses(String s) {
109+
ans = new ArrayList<>();
110+
dfs(s, new ArrayList<>());
111+
return ans;
112+
}
113+
114+
private void dfs(String s, List<String> t) {
115+
if (t.size() == 4) {
116+
if ("".equals(s)) {
117+
ans.add(String.join(".", t));
118+
}
119+
return;
120+
}
121+
for (int i = 1; i < Math.min(4, s.length() + 1); ++i) {
122+
String c = s.substring(0, i);
123+
if (check(c)) {
124+
t.add(c);
125+
dfs(s.substring(i), t);
126+
t.remove(t.size() - 1);
127+
}
128+
}
129+
}
130+
131+
private boolean check(String s) {
132+
if ("".equals(s)) {
133+
return false;
134+
}
135+
int num = Integer.parseInt(s);
136+
if (num > 255) {
137+
return false;
138+
}
139+
if (s.charAt(0) == '0' && s.length() > 1) {
140+
return false;
141+
}
142+
return true;
143+
}
144+
}
145+
```
81146

147+
### **C++**
148+
149+
```cpp
150+
class Solution {
151+
public:
152+
vector<string> restoreIpAddresses(string s) {
153+
vector<string> ans;
154+
vector<string> t;
155+
dfs(s, t, ans);
156+
return ans;
157+
}
158+
159+
void dfs(string s, vector<string>& t, vector<string>& ans) {
160+
if (t.size() == 4)
161+
{
162+
if (s == "")
163+
{
164+
string p = "";
165+
for (auto e : t) p += e + ".";
166+
p.pop_back();
167+
ans.push_back(p);
168+
}
169+
return;
170+
}
171+
for (int i = 1; i < min(4, (int) s.size() + 1); ++i)
172+
{
173+
string c = s.substr(0, i);
174+
if (check(c))
175+
{
176+
t.push_back(c);
177+
dfs(s.substr(i, s.size() - i), t, ans);
178+
t.pop_back();
179+
}
180+
}
181+
}
182+
183+
bool check(string s) {
184+
if (s == "") return false;
185+
int num = stoi(s);
186+
if (num > 255) return false;
187+
if (s[0] == '0' && s.size() > 1) return false;
188+
return true;
189+
}
190+
};
82191
```
83192

84193
### **...**

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