@@ -73,43 +73,38 @@ directory.check(2);
7373
7474<!-- solution:start -->
7575
76- ### 方法一
76+ ### 方法一:哈希表
77+ 78+ 我们可以使用一个哈希集合 ` available ` 来存储未被分配的电话号码,初始时,哈希表中存储的是 ` [0, 1, 2, ..., maxNumbers - 1] ` 。
79+ 80+ 调用 ` get ` 方法时,我们从 ` available ` 中取出一个未被分配的电话号码,如果 ` available ` 为空,则返回 ` -1 ` 。时间复杂度 $O(1)$。
81+ 82+ 调用 ` check ` 方法时,我们只需要判断 ` number ` 是否在 ` available ` 中即可。时间复杂度 $O(1)$。
83+ 84+ 调用 ` release ` 方法时,我们将 ` number ` 添加到 ` available ` 中。时间复杂度 $O(1)$。
85+ 86+ 空间复杂度 $O(n),ドル其中 $n$ 是 ` maxNumbers ` 的值。
7787
7888<!-- tabs:start -->
7989
8090#### Python3
8191
8292``` python
8393class PhoneDirectory :
94+ 8495 def __init__ (self maxNumbers : int ):
85- """
86- Initialize your data structure here
87- @param maxNumbers - The maximum numbers that can be stored in the phone directory.
88- """
89- self .provided = [False ] * maxNumbers
96+ self .available = set (range (maxNumbers))
9097
9198 def get (self int :
92- """
93- Provide a number which is not assigned to anyone.
94- @return - Return an available number. Return -1 if none is available.
95- """
96- for i in range (len (self .provided)):
97- if not self .provided[i]:
98- self .provided[i] = True
99- return i
100- return - 1
99+ if not self .available:
100+ return - 1
101+ return self .available.pop()
101102
102103 def check (self number : int ) -> bool :
103- """
104- Check if a number is available or not.
105- """
106- return not self .provided[number]
104+ return number in self .available
107105
108106 def release (self number : int ) -> None :
109- """
110- Recycle or release a number.
111- """
112- self .provided[number] = False
107+ self .available.add(number)
113108
114109
115110# Your PhoneDirectory object will be instantiated and called as such:
@@ -123,39 +118,29 @@ class PhoneDirectory:
123118
124119``` java
125120class PhoneDirectory {
121+ private Set<Integer > available = new HashSet<> ();
126122
127- private boolean [] provided;
128- 129- /**
130- Initialize your data structure here
131- @param maxNumbers - The maximum numbers that can be stored in the phone directory.
132- */
133123 public PhoneDirectory (int maxNumbers ) {
134- provided = new boolean [maxNumbers];
124+ for (int i = 0 ; i < maxNumbers; ++ i) {
125+ available. add(i);
126+ }
135127 }
136128
137- /**
138- Provide a number which is not assigned to anyone.
139- @return - Return an available number. Return -1 if none is available.
140- */
141129 public int get () {
142- for (int i = 0 ; i < provided. length; ++ i) {
143- if (! provided[i]) {
144- provided[i] = true ;
145- return i;
146- }
130+ if (available. isEmpty()) {
131+ return - 1 ;
147132 }
148- return - 1 ;
133+ int x = available. iterator(). next();
134+ available. remove(x);
135+ return x;
149136 }
150137
151- /* * Check if a number is available or not. */
152138 public boolean check (int number ) {
153- return ! provided[ number] ;
139+ return available . contains( number) ;
154140 }
155141
156- /* * Recycle or release a number. */
157142 public void release (int number ) {
158- provided[ number] = false ;
143+ available . add( number) ;
159144 }
160145}
161146
@@ -168,6 +153,127 @@ class PhoneDirectory {
168153 */
169154```
170155
156+ #### C++
157+ 158+ ``` cpp
159+ class PhoneDirectory {
160+ public:
161+ PhoneDirectory(int maxNumbers) {
162+ for (int i = 0; i < maxNumbers; ++i) {
163+ available.insert(i);
164+ }
165+ }
166+ 167+ int get() {
168+ if (available.empty()) {
169+ return -1;
170+ }
171+ int x = *available.begin();
172+ available.erase(x);
173+ return x;
174+ }
175+ 176+ bool check (int number) {
177+ return available.contains(number);
178+ }
179+ 180+ void release(int number) {
181+ available.insert(number);
182+ }
183+ 184+ private:
185+ unordered_set<int > available;
186+ };
187+ 188+ /**
189+ * Your PhoneDirectory object will be instantiated and called as such:
190+ * PhoneDirectory* obj = new PhoneDirectory(maxNumbers);
191+ * int param_1 = obj->get();
192+ * bool param_2 = obj->check(number);
193+ * obj->release(number);
194+ * /
195+ ```
196+
197+ #### Go
198+
199+ ```go
200+ type PhoneDirectory struct {
201+ available map[int]bool
202+ }
203+
204+ func Constructor(maxNumbers int) PhoneDirectory {
205+ available := make(map[int]bool)
206+ for i := 0; i < maxNumbers; i++ {
207+ available[i] = true
208+ }
209+ return PhoneDirectory{available}
210+ }
211+
212+ func (this *PhoneDirectory) Get() int {
213+ for k := range this.available {
214+ delete(this.available, k)
215+ return k
216+ }
217+ return -1
218+ }
219+
220+ func (this *PhoneDirectory) Check(number int) bool {
221+ _, ok := this.available[number]
222+ return ok
223+ }
224+
225+ func (this *PhoneDirectory) Release(number int) {
226+ this.available[number] = true
227+ }
228+
229+ /**
230+ * Your PhoneDirectory object will be instantiated and called as such:
231+ * obj := Constructor(maxNumbers);
232+ * param_1 := obj.Get();
233+ * param_2 := obj.Check(number);
234+ * obj.Release(number);
235+ */
236+ ```
237+ 238+ #### TypeScript
239+ 240+ ``` ts
241+ class PhoneDirectory {
242+ private available: Set <number > = new Set ();
243+ 244+ constructor (maxNumbers : number ) {
245+ for (let i = 0 ; i < maxNumbers ; ++ i ) {
246+ this .available .add (i );
247+ }
248+ }
249+ 250+ get(): number {
251+ const = this .available ;
252+ if (x === undefined ) {
253+ return - 1 ;
254+ }
255+ this .available .delete (x );
256+ return x ;
257+ }
258+ 259+ check(number : number ): boolean {
260+ return this .available .has (number );
261+ }
262+ 263+ release(number : number ): void {
264+ this .available .add (number );
265+ }
266+ }
267+ 268+ /**
269+ * Your PhoneDirectory object will be instantiated and called as such:
270+ * var obj = new PhoneDirectory(maxNumbers)
271+ * var param_1 = obj.get()
272+ * var param_2 = obj.check(number)
273+ * obj.release(number)
274+ */
275+ ```
276+ 171277<!-- tabs:end -->
172278
173279<!-- solution:end -->
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