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Design a Phone Directory which supports the following operations:
get: Provide a number which is not assigned to anyone.check: Check if a number is available or not.release: Recycle or release a number.Example:
// Init a phone directory containing a total of 3 numbers: 0, 1, and 2. PhoneDirectory directory = new PhoneDirectory(3); // It can return any available phone number. Here we assume it returns 0. directory.get(); // Assume it returns 1. directory.get(); // The number 2 is available, so return true. directory.check(2); // It returns 2, the only number that is left. directory.get(); // The number 2 is no longer available, so return false. directory.check(2); // Release number 2 back to the pool. directory.release(2); // Number 2 is available again, return true. directory.check(2);
1 public class PhoneDirectory { 2 HashSet<Integer> numReleased; 3 int maxNum, nextUnuse; 4 5 6 /** Initialize your data structure here 7 @param maxNumbers - The maximum numbers that can be stored in the phone directory. */ 8 public PhoneDirectory(int maxNumbers) { 9 numReleased = new HashSet<Integer>(); 10 maxNum = maxNumbers; 11 nextUnuse = 0; 12 13 } 14 15 /** Provide a number which is not assigned to anyone. 16 @return - Return an available number. Return -1 if none is available. */ 17 public int get() { 18 int num = -1; 19 if (!numReleased.isEmpty()) { 20 for (Integer i : numReleased) { 21 num = i; 22 break; 23 } 24 numReleased.remove(num); 25 } else if (nextUnuse < maxNum) { 26 num = nextUnuse++; 27 } 28 return num; 29 } 30 31 /** Check if a number is available or not. */ 32 public boolean check(int number) { 33 if (number >= maxNum) return false; 34 35 if (number >= nextUnuse || numReleased.contains(number)) return true; 36 37 return false; 38 } 39 40 /** Recycle or release a number. */ 41 public void release(int number) { 42 if (number >= nextUnuse) return; 43 numReleased.add(number); 44 } 45 } 46 47 /** 48 * Your PhoneDirectory object will be instantiated and called as such: 49 * PhoneDirectory obj = new PhoneDirectory(maxNumbers); 50 * int param_1 = obj.get(); 51 * boolean param_2 = obj.check(number); 52 * obj.release(number); 53 */
LeetCode-Design Phone Directory
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原文地址：http://www.cnblogs.com/lishiblog/p/5748931.html
