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Commit 529aa83

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feat: add solutions to lc problem: No.0929 (doocs#3857)
No.0929.Unique Email Addresses
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‎solution/0900-0999/0929.Unique Email Addresses/README.md‎

Lines changed: 107 additions & 82 deletions
Original file line numberDiff line numberDiff line change
@@ -79,7 +79,11 @@ tags:
7979

8080
### 方法一:哈希表
8181

82-
利用哈希表存放转换后的电子邮件,最后返回哈希表的 size 即可。
82+
我们可以用一个哈希表 $s$ 来存储所有的电子邮件地址,然后遍历数组 $\textit{emails},ドル对于每个电子邮件地址,我们将其分为本地名和域名两部分,然后对本地名进行处理,去掉所有的点号和加号后面的字符,最后将处理后的本地名和域名拼接起来,加入哈希表 $s$ 中。
83+
84+
最后返回哈希表 $s$ 的大小即可。
85+
86+
时间复杂度 $O(L),ドル空间复杂度 $O(L),ドル其中 $L$ 为所有电子邮件地址的长度之和。
8387

8488
<!-- tabs:start -->
8589

@@ -90,11 +94,15 @@ class Solution:
9094
def numUniqueEmails(self, emails: List[str]) -> int:
9195
s = set()
9296
for email in emails:
93-
local, domain = email.split('@')
94-
local = local.replace('.', '')
95-
if (i := local.find('+')) != -1:
96-
local = local[:i]
97-
s.add(local + '@' + domain)
97+
local, domain = email.split("@")
98+
t = []
99+
for c in local:
100+
if c == ".":
101+
continue
102+
if c == "+":
103+
break
104+
t.append(c)
105+
s.add("".join(t) + "@" + domain)
98106
return len(s)
99107
```
100108

@@ -105,14 +113,20 @@ class Solution {
105113
public int numUniqueEmails(String[] emails) {
106114
Set<String> s = new HashSet<>();
107115
for (String email : emails) {
108-
String[] t = email.split("@");
109-
String local = t[0].replace(".", "");
110-
String domain = t[1];
111-
int i = local.indexOf('+');
112-
if (i != -1) {
113-
local = local.substring(0, i);
116+
String[] parts = email.split("@");
117+
String local = parts[0];
118+
String domain = parts[1];
119+
StringBuilder t = new StringBuilder();
120+
for (char c : local.toCharArray()) {
121+
if (c == '.') {
122+
continue;
123+
}
124+
if (c == '+') {
125+
break;
126+
}
127+
t.append(c);
114128
}
115-
s.add(local + "@" + domain);
129+
s.add(t.toString() + "@" + domain);
116130
}
117131
return s.size();
118132
}
@@ -126,15 +140,21 @@ class Solution {
126140
public:
127141
int numUniqueEmails(vector<string>& emails) {
128142
unordered_set<string> s;
129-
for (auto& email : emails) {
130-
int i = email.find('@');
131-
string local = email.substr(0, i);
132-
string domain = email.substr(i + 1);
133-
i = local.find('+', 0);
134-
if (~i) local = local.substr(0, i);
135-
while (~(i = local.find('.', 0)))
136-
local.erase(local.begin() + i);
137-
s.insert(local + "@" + domain);
143+
for (const string& email : emails) {
144+
size_t atPos = email.find('@');
145+
string local = email.substr(0, atPos);
146+
string domain = email.substr(atPos + 1);
147+
string t;
148+
for (char c : local) {
149+
if (c == '.') {
150+
continue;
151+
}
152+
if (c == '+') {
153+
break;
154+
}
155+
t.push_back(c);
156+
}
157+
s.insert(t + "@" + domain);
138158
}
139159
return s.size();
140160
}
@@ -145,13 +165,22 @@ public:
145165
146166
```go
147167
func numUniqueEmails(emails []string) int {
148-
s := map[string]bool{}
168+
s := make(map[string]struct{})
149169
for _, email := range emails {
150-
i := strings.IndexByte(email, '@')
151-
local := strings.SplitN(email[:i], "+", 2)[0]
152-
local = strings.ReplaceAll(local, ".", "")
153-
domain := email[i:]
154-
s[local+domain] = true
170+
parts := strings.Split(email, "@")
171+
local := parts[0]
172+
domain := parts[1]
173+
var t strings.Builder
174+
for _, c := range local {
175+
if c == '.' {
176+
continue
177+
}
178+
if c == '+' {
179+
break
180+
}
181+
t.WriteByte(byte(c))
182+
}
183+
s[t.String()+"@"+domain] = struct{}{}
155184
}
156185
return len(s)
157186
}
@@ -161,84 +190,80 @@ func numUniqueEmails(emails []string) int {
161190

162191
```ts
163192
function numUniqueEmails(emails: string[]): number {
164-
return new Set(
165-
emails
166-
.map(email => email.split('@'))
167-
.map(([start, end]) => start.replace(/\+.*|\./g, '') + '@' + end),
168-
).size;
193+
const s = new Set<string>();
194+
for (const email of emails) {
195+
const [local, domain] = email.split('@');
196+
let t = '';
197+
for (const c of local) {
198+
if (c === '.') {
199+
continue;
200+
}
201+
if (c === '+') {
202+
break;
203+
}
204+
t += c;
205+
}
206+
s.add(t + '@' + domain);
207+
}
208+
return s.size;
169209
}
170210
```
171211

172212
#### Rust
173213

174214
```rust
175215
use std::collections::HashSet;
216+
176217
impl Solution {
177218
pub fn num_unique_emails(emails: Vec<String>) -> i32 {
178-
let mut set = HashSet::new();
179-
for email in emails.iter() {
180-
let res: Vec<&str> = email.split('@').collect();
181-
let mut s = String::new();
182-
for &c in res[0].as_bytes().iter() {
183-
if c == b'.' {
219+
let mut s = HashSet::new();
220+
221+
for email in emails {
222+
let parts: Vec<&str> = email.split('@').collect();
223+
let local = parts[0];
224+
let domain = parts[1];
225+
let mut t = String::new();
226+
for c in local.chars() {
227+
if c == '.' {
184228
continue;
185229
}
186-
if c == b'+' {
230+
if c == '+' {
187231
break;
188232
}
189-
s.push(caschar);
233+
t.push(c);
190234
}
191-
s.push('@');
192-
s.push_str(res[1]);
193-
set.insert(s);
235+
s.insert(format!("{}@{}", t, domain));
194236
}
195-
set.len() as i32
237+
238+
s.len() as i32
196239
}
197240
}
198241
```
199242

200243
#### JavaScript
201244

202245
```js
203-
const numUniqueEmails2 = function (emails) {
204-
const emailFilter = function (str) {
205-
let index = str.search(/@/);
206-
let s = str.substring(0, index);
207-
let s2 = str.substring(index + 1, str.length);
208-
let res = '';
209-
for (let i = 0; i < s.length; i++) {
210-
if (s[i] === '+') break;
211-
if (s[i] === '.') continue;
212-
res = res + s[i];
213-
}
214-
return res + s2;
215-
};
216-
217-
let arr = [];
218-
for (let i = 0; i < emails.length; i++) {
219-
let t = emailFilter(emails[i]);
220-
if (arr.indexOf(t) === -1) {
221-
arr.push(t);
246+
/**
247+
* @param {string[]} emails
248+
* @return {number}
249+
*/
250+
var numUniqueEmails = function (emails) {
251+
const s = new Set();
252+
for (const email of emails) {
253+
const [local, domain] = email.split('@');
254+
let t = '';
255+
for (const c of local) {
256+
if (c === '.') {
257+
continue;
258+
}
259+
if (c === '+') {
260+
break;
261+
}
262+
t += c;
222263
}
264+
s.add(t + '@' + domain);
223265
}
224-
return arr.length;
225-
};
226-
227-
const numUniqueEmails = function (emails) {
228-
let arr = emails.map(str => {
229-
let index = str.search(/@/);
230-
let s = str.substring(0, index);
231-
let s2 = str.substring(index + 1, str.length);
232-
let res = '';
233-
for (let i = 0; i < s.length; i++) {
234-
if (s[i] === '+') break;
235-
if (s[i] === '.') continue;
236-
res = res + s[i];
237-
}
238-
return res + s2;
239-
});
240-
let set = new Set(arr);
241-
return set.size;
266+
return s.size;
242267
};
243268
```
244269

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