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Commit ab2ddaf

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feat: add solutions to lc problem: No.0481
No.0481.Magical String
1 parent afd770d commit ab2ddaf

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6 files changed

+251
-2
lines changed

6 files changed

+251
-2
lines changed

‎solution/0400-0499/0481.Magical String/README.md‎

Lines changed: 88 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -45,22 +45,109 @@
4545

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<!-- 这里可写通用的实现逻辑 -->
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**方法一:模拟**
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直接模拟字符串添加。
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时间复杂度 $O(n),ドル空间复杂度 $O(n)$。
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4854
<!-- 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
55-
61+
class Solution:
62+
def magicalString(self, n: int) -> int:
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s = list('1221121')
64+
i = 5
65+
while len(s) < n:
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if s[i] == '1':
67+
s.append('2' if s[-1] == '1' else '1')
68+
else:
69+
s.extend(list('22' if s[-1] == '1' else '11'))
70+
i += 1
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return s[:n].count('1')
5672
```
5773

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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
79+
class Solution {
80+
public int magicalString(int n) {
81+
StringBuilder s = new StringBuilder("1221121");
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int i = 5;
83+
while (s.length() < n) {
84+
char c = s.charAt(s.length() - 1);
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if (s.charAt(i) == '1') {
86+
s.append(c == '1' ? '2' : '1');
87+
} else {
88+
s.append(c == '1' ? "22" : "11");
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}
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++i;
91+
}
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int ans = 0;
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for (i = 0; i < n; ++i) {
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if (s.charAt(i) == '1') {
95+
++ans;
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}
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}
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return ans;
99+
}
100+
}
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```
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### **C++**
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```cpp
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class Solution {
107+
public:
108+
int magicalString(int n) {
109+
string s = "1221121";
110+
int i = 5;
111+
while (s.size() < n) {
112+
if (s[i] == '1') {
113+
s += s.back() == '1' ? "2" : "1";
114+
} else {
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s += s.back() == '1' ? "22" : "11";
116+
}
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++i;
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}
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return count(s.begin(), s.begin() + n, '1');
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}
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};
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```
63123
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### **Go**
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```go
127+
func magicalString(n int) int {
128+
s := []byte("1221121")
129+
i := 5
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for len(s) < n {
131+
c := s[len(s)-1]
132+
if s[i] == '1' {
133+
if c == '1' {
134+
s = append(s, '2')
135+
} else {
136+
s = append(s, '1')
137+
}
138+
} else {
139+
if c == '1' {
140+
s = append(s, '2')
141+
s = append(s, '2')
142+
} else {
143+
s = append(s, '1')
144+
s = append(s, '1')
145+
}
146+
}
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i++
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}
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return bytes.Count(s[:n], []byte("1"))
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}
64151
```
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66153
### **...**

‎solution/0400-0499/0481.Magical String/README_EN.md‎

Lines changed: 82 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -44,13 +44,94 @@
4444
### **Python3**
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```python
47-
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class Solution:
48+
def magicalString(self, n: int) -> int:
49+
s = list('1221121')
50+
i = 5
51+
while len(s) < n:
52+
if s[i] == '1':
53+
s.append('2' if s[-1] == '1' else '1')
54+
else:
55+
s.extend(list('22' if s[-1] == '1' else '11'))
56+
i += 1
57+
return s[:n].count('1')
4858
```
4959

5060
### **Java**
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5262
```java
63+
class Solution {
64+
public int magicalString(int n) {
65+
StringBuilder s = new StringBuilder("1221121");
66+
int i = 5;
67+
while (s.length() < n) {
68+
char c = s.charAt(s.length() - 1);
69+
if (s.charAt(i) == '1') {
70+
s.append(c == '1' ? '2' : '1');
71+
} else {
72+
s.append(c == '1' ? "22" : "11");
73+
}
74+
++i;
75+
}
76+
int ans = 0;
77+
for (i = 0; i < n; ++i) {
78+
if (s.charAt(i) == '1') {
79+
++ans;
80+
}
81+
}
82+
return ans;
83+
}
84+
}
85+
```
86+
87+
### **C++**
88+
89+
```cpp
90+
class Solution {
91+
public:
92+
int magicalString(int n) {
93+
string s = "1221121";
94+
int i = 5;
95+
while (s.size() < n) {
96+
if (s[i] == '1') {
97+
s += s.back() == '1' ? "2" : "1";
98+
} else {
99+
s += s.back() == '1' ? "22" : "11";
100+
}
101+
++i;
102+
}
103+
return count(s.begin(), s.begin() + n, '1');
104+
}
105+
};
106+
```
53107
108+
### **Go**
109+
110+
```go
111+
func magicalString(n int) int {
112+
s := []byte("1221121")
113+
i := 5
114+
for len(s) < n {
115+
c := s[len(s)-1]
116+
if s[i] == '1' {
117+
if c == '1' {
118+
s = append(s, '2')
119+
} else {
120+
s = append(s, '1')
121+
}
122+
} else {
123+
if c == '1' {
124+
s = append(s, '2')
125+
s = append(s, '2')
126+
} else {
127+
s = append(s, '1')
128+
s = append(s, '1')
129+
}
130+
}
131+
i++
132+
}
133+
return bytes.Count(s[:n], []byte("1"))
134+
}
54135
```
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56137
### **...**
Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,16 @@
1+
class Solution {
2+
public:
3+
int magicalString(int n) {
4+
string s = "1221121";
5+
int i = 5;
6+
while (s.size() < n) {
7+
if (s[i] == '1') {
8+
s += s.back() == '1' ? "2" : "1";
9+
} else {
10+
s += s.back() == '1' ? "22" : "11";
11+
}
12+
++i;
13+
}
14+
return count(s.begin(), s.begin() + n, '1');
15+
}
16+
};
Lines changed: 24 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
func magicalString(n int) int {
2+
s := []byte("1221121")
3+
i := 5
4+
for len(s) < n {
5+
c := s[len(s)-1]
6+
if s[i] == '1' {
7+
if c == '1' {
8+
s = append(s, '2')
9+
} else {
10+
s = append(s, '1')
11+
}
12+
} else {
13+
if c == '1' {
14+
s = append(s, '2')
15+
s = append(s, '2')
16+
} else {
17+
s = append(s, '1')
18+
s = append(s, '1')
19+
}
20+
}
21+
i++
22+
}
23+
return bytes.Count(s[:n], []byte("1"))
24+
}
Lines changed: 30 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,30 @@
1+
class Solution {
2+
public int magicalString(int n) {
3+
StringBuilder s = new StringBuilder("1221121");
4+
int i = 5;
5+
while (s.length() < n) {
6+
char c = s.charAt(s.length() - 1);
7+
if (s.charAt(i) == '1') {
8+
if (c == '1') {
9+
s.append('2');
10+
} else {
11+
s.append('1');
12+
}
13+
} else {
14+
if (c == '1') {
15+
s.append("22");
16+
} else {
17+
s.append("11");
18+
}
19+
}
20+
++i;
21+
}
22+
int ans = 0;
23+
for (i = 0; i < n; ++i) {
24+
if (s.charAt(i) == '1') {
25+
++ans;
26+
}
27+
}
28+
return ans;
29+
}
30+
}
Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
class Solution:
2+
def magicalString(self, n: int) -> int:
3+
s = list('1221121')
4+
i = 5
5+
while len(s) < n:
6+
if s[i] == '1':
7+
s.append('2' if s[-1] == '1' else '1')
8+
else:
9+
s.extend(list('22' if s[-1] == '1' else '11'))
10+
i += 1
11+
return s[:n].count('1')

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