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Commit 4228f65

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feat: add solutions to lc problem: No.2211
No.2211.Count Collisions on a Road
1 parent 8707e85 commit 4228f65

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9 files changed

+146
-64
lines changed

9 files changed

+146
-64
lines changed

‎solution/2200-2299/2211.Count Collisions on a Road/README.md‎

Lines changed: 53 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -58,7 +58,9 @@
5858

5959
<!-- 这里可写通用的实现逻辑 -->
6060

61-
这个题比较有意思,最后规律是左边向左的车辆可以出去,右边向右的车辆可以出去,中间不是 S 的都出不来。
61+
- 去除前缀为 `L` 的字符;
62+
- 去除后缀为 `R` 的字符;
63+
- 剩余的字符串中,除了 `S` 以外的字符,都会贡献一次碰撞次数。
6264

6365
<!-- tabs:start -->
6466

@@ -69,15 +71,8 @@
6971
```python
7072
class Solution:
7173
def countCollisions(self, directions: str) -> int:
72-
l, r = 0, len(directions)-1
73-
while l <= r and directions[l] == 'L':
74-
l += 1
75-
while l <= r and directions[r] == 'R':
76-
r -= 1
77-
count = 0
78-
for i in range(l, r+1):
79-
count += directions[i] != 'S'
80-
return count
74+
d = directions.lstrip('L').rstrip('R')
75+
return len(d) - d.count('S')
8176
```
8277

8378
### **Java**
@@ -87,25 +82,48 @@ class Solution:
8782
```java
8883
class Solution {
8984
public int countCollisions(String directions) {
90-
int l = 0, r = directions.length() - 1, count = 0;
91-
while (l <= r && directions.substring(l, l + 1).equals("L")) {
92-
l++;
85+
char[] ds = directions.toCharArray();
86+
int n = ds.length;
87+
int l = 0;
88+
int r = n - 1;
89+
while (l < n && ds[l] == 'L') {
90+
++l;
9391
}
94-
while (l <= r && directions.substring(r, r +1).equals("R")) {
95-
r--;
92+
while (r >=0 && ds[r] =='R') {
93+
--r;
9694
}
97-
for (int i = l; i <= r; i++) {
98-
if (!directions.substring(i, i + 1).equals("S")) count += 1;
95+
int ans = 0;
96+
for (int i = l; i <= r; ++i) {
97+
if (ds[i] != 'S') {
98+
++ans;
99+
}
99100
}
100-
return count;
101+
return ans;
101102
}
102103
}
103104
```
104105

105106
### **TypeScript**
106107

107108
```ts
108-
109+
function countCollisions(directions: string): number {
110+
const n = directions.length;
111+
let l = 0,
112+
r = n - 1;
113+
while (l < n && directions[l] == 'L') {
114+
++l;
115+
}
116+
while (r >= 0 && directions[r] == 'R') {
117+
--r;
118+
}
119+
let ans = 0;
120+
for (let i = l; i <= r; ++i) {
121+
if (directions[i] != 'S') {
122+
++ans;
123+
}
124+
}
125+
return ans;
126+
}
109127
```
110128

111129
### **C++**
@@ -130,4 +148,20 @@ public:
130148
};
131149
```
132150

151+
### **Go**
152+
153+
```go
154+
func countCollisions(directions string) int {
155+
d := strings.TrimLeft(directions, "L")
156+
d = strings.TrimRight(d, "R")
157+
return len(d) - strings.Count(d, "S")
158+
}
159+
```
160+
161+
### **...**
162+
163+
```
164+
165+
```
166+
133167
<!-- tabs:end -->

‎solution/2200-2299/2211.Count Collisions on a Road/README_EN.md‎

Lines changed: 50 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -59,41 +59,57 @@ No cars will collide with each other. Thus, the total number of collisions that
5959
```python
6060
class Solution:
6161
def countCollisions(self, directions: str) -> int:
62-
l, r = 0, len(directions)-1
63-
while l <= r and directions[l] == 'L':
64-
l += 1
65-
while l <= r and directions[r] == 'R':
66-
r -= 1
67-
count = 0
68-
for i in range(l, r+1):
69-
count += directions[i] != 'S'
70-
return count
62+
d = directions.lstrip('L').rstrip('R')
63+
return len(d) - d.count('S')
7164
```
7265

7366
### **Java**
7467

7568
```java
7669
class Solution {
7770
public int countCollisions(String directions) {
78-
int l = 0, r = directions.length() - 1, count = 0;
79-
while (l <= r && directions.substring(l, l + 1).equals("L")) {
80-
l++;
71+
char[] ds = directions.toCharArray();
72+
int n = ds.length;
73+
int l = 0;
74+
int r = n - 1;
75+
while (l < n && ds[l] == 'L') {
76+
++l;
8177
}
82-
while (l <= r && directions.substring(r, r +1).equals("R")) {
83-
r--;
78+
while (r >=0 && ds[r] =='R') {
79+
--r;
8480
}
85-
for (int i = l; i <= r; i++) {
86-
if (!directions.substring(i, i + 1).equals("S")) count += 1;
81+
int ans = 0;
82+
for (int i = l; i <= r; ++i) {
83+
if (ds[i] != 'S') {
84+
++ans;
85+
}
8786
}
88-
return count;
87+
return ans;
8988
}
9089
}
9190
```
9291

9392
### **TypeScript**
9493

9594
```ts
96-
95+
function countCollisions(directions: string): number {
96+
const n = directions.length;
97+
let l = 0,
98+
r = n - 1;
99+
while (l < n && directions[l] == 'L') {
100+
++l;
101+
}
102+
while (r >= 0 && directions[r] == 'R') {
103+
--r;
104+
}
105+
let ans = 0;
106+
for (let i = l; i <= r; ++i) {
107+
if (directions[i] != 'S') {
108+
++ans;
109+
}
110+
}
111+
return ans;
112+
}
97113
```
98114

99115
### **C++**
@@ -118,4 +134,20 @@ public:
118134
};
119135
```
120136

137+
### **Go**
138+
139+
```go
140+
func countCollisions(directions string) int {
141+
d := strings.TrimLeft(directions, "L")
142+
d = strings.TrimRight(d, "R")
143+
return len(d) - strings.Count(d, "S")
144+
}
145+
```
146+
147+
### **...**
148+
149+
```
150+
151+
```
152+
121153
<!-- tabs:end -->
Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
1+
func countCollisions(directions string) int {
2+
d := strings.TrimLeft(directions, "L")
3+
d = strings.TrimRight(d, "R")
4+
return len(d) - strings.Count(d, "S")
5+
}
Lines changed: 15 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,21 @@
11
class Solution {
22
public int countCollisions(String directions) {
3-
int l = 0, r = directions.length() - 1, count = 0;
4-
while (l <= r && directions.substring(l, l + 1).equals("L")) {
5-
l++;
3+
char[] ds = directions.toCharArray();
4+
int n = ds.length;
5+
int l = 0;
6+
int r = n - 1;
7+
while (l < n && ds[l] == 'L') {
8+
++l;
69
}
7-
while (l <= r && directions.substring(r, r + 1).equals("R")) {
8-
r--;
10+
while (r >= 0 && ds[r] == 'R') {
11+
--r;
912
}
10-
for (int i = l; i <= r; i++) {
11-
if (!directions.substring(i, i + 1).equals("S")) count += 1;
13+
int ans = 0;
14+
for (int i = l; i <= r; ++i) {
15+
if (ds[i] != 'S') {
16+
++ans;
17+
}
1218
}
13-
return count;
19+
return ans;
1420
}
15-
}
21+
}
Lines changed: 2 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,4 @@
11
class Solution:
22
def countCollisions(self, directions: str) -> int:
3-
l, r = 0, len(directions)-1
4-
while l <= r and directions[l] == 'L':
5-
l += 1
6-
while l <= r and directions[r] == 'R':
7-
r -= 1
8-
count = 0
9-
for i in range(l, r+1):
10-
count += directions[i] != 'S'
11-
return count
3+
d = directions.lstrip('L').rstrip('R')
4+
return len(d) - d.count('S')
Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
function countCollisions(directions: string): number {
2+
const n = directions.length;
3+
let l = 0,
4+
r = n - 1;
5+
while (l < n && directions[l] == 'L') {
6+
++l;
7+
}
8+
while (r >= 0 && directions[r] == 'R') {
9+
--r;
10+
}
11+
let ans = 0;
12+
for (let i = l; i <= r; ++i) {
13+
if (directions[i] != 'S') {
14+
++ans;
15+
}
16+
}
17+
return ans;
18+
}

‎solution/2200-2299/2213.Longest Substring of One Repeating Character/README.md‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -150,9 +150,7 @@ class SegmentTree:
150150
root.mx = max(root.mx, left.rmx + right.lmx)
151151

152152
def pushup(self, u):
153-
root = tr[u]
154-
left, right = tr[u << 1], tr[u << 1 | 1]
155-
self._pushup(root, left, right)
153+
self._pushup(tr[u], tr[u << 1], tr[u << 1 | 1])
156154

157155

158156
class Solution:

‎solution/2200-2299/2213.Longest Substring of One Repeating Character/README_EN.md‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -129,9 +129,7 @@ class SegmentTree:
129129
root.mx = max(root.mx, left.rmx + right.lmx)
130130

131131
def pushup(self, u):
132-
root = tr[u]
133-
left, right = tr[u << 1], tr[u << 1 | 1]
134-
self._pushup(root, left, right)
132+
self._pushup(tr[u], tr[u << 1], tr[u << 1 | 1])
135133

136134

137135
class Solution:

‎solution/2200-2299/2213.Longest Substring of One Repeating Character/Solution.py‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -71,9 +71,7 @@ def _pushup(self, root, left, right):
7171
root.mx = max(root.mx, left.rmx + right.lmx)
7272

7373
def pushup(self, u):
74-
root = tr[u]
75-
left, right = tr[u << 1], tr[u << 1 | 1]
76-
self._pushup(root, left, right)
74+
self._pushup(tr[u], tr[u << 1], tr[u << 1 | 1])
7775

7876

7977
class Solution:

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